インストールエラーについて

gnuplotをインストールしたく、tarファイルを解凍した後、ターミナルで
./configure
を実行したところ以下のようなエラーをはきましたので、
以下のサイトからQtのダウンロードを行いました。
http://www.qt.io/download-open-source/
しかし依然エラーはそのままです。

ちなみにパスを通すために
PKG_CONFIG_PATH=/opt/X11/lib/pkgconfig ./configure
として実行しています。

どうすればエラーが解消されますでしょうか。かなり困っているので、解答頂けるととても嬉しいです。

lang
1configure: WARNING:
2Package requirements (Qt5Core Qt5Gui Qt5Network Qt5Svg Qt5PrintSupport) were not met:
3
4No package 'Qt5Core' found
5No package 'Qt5Gui' found
6No package 'Qt5Network' found
7No package 'Qt5Svg' found
8No package 'Qt5PrintSupport' found
9
10Consider adjusting the PKG_CONFIG_PATH environment variable if you
11installed software in a non-standard prefix.
12
13Alternatively, you may set the environment variables QT_CFLAGS
14and QT_LIBS to avoid the need to call pkg-config.
15See the pkg-config man page for more details.
16
17checking for QT... configure: WARNING:
18Package requirements (QtCore >= 4.5 QtGui >= 4.5 QtNetwork >= 4.5 QtSvg >= 4.5) were not met:
19
20No package 'QtCore' found
21No package 'QtGui' found
22No package 'QtNetwork' found
23No package 'QtSvg' found
24
25Consider adjusting the PKG_CONFIG_PATH environment variable if you
26installed software in a non-standard prefix.
27
28Alternatively, you may set the environment variables QT_CFLAGS
29and QT_LIBS to avoid the need to call pkg-config.
30See the pkg-config man page for more details.
31
32configure: WARNING: The Qt terminal will not be compiled.
33checking that generated files are newer than configure... done
34configure: creating ./config.status
35config.status: creating Makefile
36config.status: creating config/Makefile
37config.status: creating demo/Makefile
38config.status: creating demo/plugin/Makefile
39config.status: creating docs/Makefile
40config.status: creating m4/Makefile
41config.status: creating man/Makefile
42config.status: creating share/Makefile
43config.status: creating share/LaTeX/Makefile
44config.status: creating src/Makefile
45config.status: creating src/beos/Makefile
46config.status: creating src/wxterminal/Makefile
47config.status: creating src/qtterminal/Makefile
48config.status: creating term/Makefile
49config.status: creating tutorial/Makefile
50config.status: creating config.h
51config.status: config.h is unchanged
52config.status: executing depfiles commands
53config.status: executing default commands
54
55** Configuration summary for gnuplot 5.0.0:
56
57gnuplot will be compiled with the following terminals:
58
59  Standalone terminals: yes (always builtin)
60    canvas, cgm, context, corel, dumb, dxf, eepic, emf, emtex,
61    epslatex, fig, hpgl,latex, metafont, metapost, mif, pcl5,
62    postscript, pslatex, pstex, pstricks, qms, svg,
63    tek40xx, tek410x, texdraw, tgif, tkcanvas, tpic, vttek
64
65  dot-matrix terminals: no (use --with-bitmap-terminals to enable)
66    epson, nec, okidata, tandy, and seiko dp414 printers
67    hp500c, hpdj, hpljii, hppj, pbm, sixel, starc
68
69  X Window System terminal: yes
70    (with multi-byte fonts)
71    (enable plotting to windows opened by external apps) 
72    (with application defaults, in /etc/X11/app-defaults/)
73  PDFlib pdf terminal: no (use --with-pdf to enable)
74  linux terminal (vga console): no (use --with-linux-vga to enable)
75  vgagl terminal ((s)vga console): no (use --with-linux-vga to enable)
76  ggi terminal: no (use --with-ggi to enable, requires libggi)
77  gpic terminal: no   (use --with-gpic to enable)
78  mif terminal: no   (use --with-mif to enable)
79  caca terminal: no (requires libcaca >= 0.99.beta15)
80  aqua terminal (OSX): no
81  libgd-based png, jpeg, and gif terminals: yes (with animated gif)
82  cairo-based pdf and png terminals: yes 
83  lua/TikZ terminal: yes 
84  wxt terminal: yes 
85  Qt terminal: no (use --with-qt or --with-qt=qt4 to enable
86
87  Additional platform-specific or older terminals omitted by default:
88   gpic, mif (FrameMaker 3), hp2623a, hp2648, imagen, kyocera 
89   pm (makefile.os2), be (BeOS), svga (MSDOS/djgpp)
90   sun, windows (several options)
91
92gnuplot will be compiled with the following configurable features:
93
94  Mouse support in interactive terminals: yes
95  Typing <space> in plot window raises console
96  Maximum number of parallel axes: 5 
97  Placement of rectangles and other objects: yes 
98  Readline library: GNU readline library with  -lncurses
99  Command-line history file: yes
100  Check current directory for .gnuplot file: no (use --with-cwdrc to enable)
101  Sort help/subtopic tables by column: no (use --without-row-help to enable)
102  cerf() and other special functions from libcerf: yes
103  plugin support for loading external functions: yes 
104  Use TeX kpsexpand to search for fonts: no (use --with-kpsexpand to enable)
105  Hidden3d optimization (gridbox/quadtree/none): quadtree
106  Allow deprecated syntax: no (use --enable-backwards-compatibility)
107  Statistical summary of data ("stats" command): yes
108
109gnuplot will install the following additional materials:
110
111  LaTeX tutorial: no
112  cfg file for epslatex terminal: yes
113  TeX *.sty for lua/tikz terminal: yes
114  TeX files will be installed in /usr/local/texlive/texmf-local/tex/latex/gnuplot
115                               (use --with-texdir=DIR to change)
116  Help file: yes (always), in ${datarootdir}/gnuplot/5.0/gnuplot.gih
117  PostScript prologue files: yes (always)
118