CMake: Build glfw separately with CMake

Makes it easier to support Wayland later on.

.travis.yml

@@ -25,11 +25,12 @@ before_install:
       sudo apt-get install -y gcc-multilib
                               libasound2-dev:$ARCH
                               libxcursor-dev:$ARCH libxinerama-dev:$ARCH mesa-common-dev:$ARCH
-                              libx11-dev:$ARCH libxrandr-dev:$ARCH libxi-dev:$ARCH
+                              libx11-dev:$ARCH libxrandr-dev:$ARCH libxrandr2:$ARCH libxi-dev:$ARCH
                               libgl1-mesa-dev:$ARCH libglu1-mesa-dev:$ARCH;
+      if [ "$ARCH" == "i386" ]; then
+        export CMAKE_ARCH_ARGS='-DCMAKE_C_FLAGS=-m32 -DCMAKE_SYSTEM_LIBRARY_PATH=/usr/lib/i386-linux-gnu';
+      fi;
       export RAYLIB_PACKAGE_SUFFIX="-Linux-$ARCH";
-      if [ "$ARCH" == "i386" ]; then export CFLAGS="-m32"; fi;
-      if [ "$ARCH" == "amd64" ]; then export CFLAGS="-m64"; fi;
       if [ "$GLFW" == "SYSTEM" ]; then
         wget 'http://ftp.de.debian.org/debian/pool/main/g/glfw3/libglfw3_3.2.1-1_amd64.deb';
         wget 'http://ftp.de.debian.org/debian/pool/main/g/glfw3/libglfw3-dev_3.2.1-1_amd64.deb';
@@ -45,7 +46,7 @@ before_install:
 script:
   - mkdir build
   - cd build
-  - cmake -DMACOS_FATLIB=ON -DSTATIC=ON -DSHARED=ON -DBUILD_EXAMPLES=ON -DBUILD_GAMES=ON -DUSE_EXTERNAL_GLFW=IF_POSSIBLE ..
+  - cmake $CMAKE_ARCH_ARGS -DMACOS_FATLIB=ON -DSTATIC=ON -DSHARED=ON -DBUILD_EXAMPLES=ON -DBUILD_GAMES=ON -DUSE_EXTERNAL_GLFW=IF_POSSIBLE ..
   - make VERBOSE=1
   - make package