Auto merge of #20249 - veeg:dev-dependency-fedora, r=jdm

Add mesa-libGLU-devel dependency to README.md

Installing all listed dependencies on fedora results in
a compilation error, due to missing mesa-libGLU-devel dependency.
This dependency is part of some of the other distributions,
with other names of course.

<!-- Please describe your changes on the following line: -->
Compiling Servo on my Fedora 26 machine after installing the developer dependencies, resulted in a failed compilation of `servo-skia-0.30000013.0` due to missing devel library.
```
/home/veeg/.cargo/registry/src/github.com-1ecc6299db9ec823/servo-skia-0.30000013.0/src/gpu/gl/unix/SkNativeGLContext_unix.cpp:10:10: fatal error: GL/glu.h: No such file or directory
 #include <GL/glu.h>
          ^~~~~~~~~~
compilation terminated.
gmake[2]: *** [CMakeFiles/skia.dir/build.make:7383: CMakeFiles/skia.dir/src/gpu/gl/unix/SkNativeGLContext_unix.cpp.o] Error 1
gmake[2]: *** Waiting for unfinished jobs....
gmake[1]: *** [CMakeFiles/Makefile2:68: CMakeFiles/skia.dir/all] Error 2
gmake: *** [Makefile:130: all] Error 2
thread 'main' panicked at '
command did not execute successfully, got: exit code: 2

build script failed, must exit now', /home/veeg/.cargo/registry/src/github.com-1ecc6299db9ec823/cmake-0.1.29/src/lib.rs:632:5
note: Run with `RUST_BACKTRACE=1` for a backtrace.

warning: build failed, waiting for other jobs to finish...
error: build failed
```

```
$ dnf provides -q /usr/include/GL/glu.h
mesa-libGLU-devel-9.0.0-11.fc26.i686 : Development files for mesa-libGLU
Repo        : fedora
Matched from:
Filename    : /usr/include/GL/glu.h

mesa-libGLU-devel-9.0.0-11.fc26.x86_64 : Development files for mesa-libGLU
Repo        : fedora
Matched from:
Filename    : /usr/include/GL/glu.h
```

Installing `mesa-libGLU-devel` solved the issue.

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix # (not applicable)

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- [X] These changes do not require tests because only README.md is affected

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README.md

@@ -99,7 +99,7 @@ sudo dnf install curl libtool gcc-c++ libXi-devel \
     freetype-devel mesa-libGL-devel mesa-libEGL-devel glib2-devel libX11-devel libXrandr-devel gperf \
     fontconfig-devel cabextract ttmkfdir python python-virtualenv python-pip expat-devel \
     rpm-build openssl-devel cmake bzip2-devel libXcursor-devel libXmu-devel mesa-libOSMesa-devel \
-    dbus-devel ncurses-devel harfbuzz-devel ccache
+    dbus-devel ncurses-devel harfbuzz-devel ccache mesa-libGLU-devel
 ```
 #### On CentOS