Modernise CMake

* Use `GNUInstallDirs` in order to respect GNU conventions.
  This is especially important for multi-arch/multi-lib setups.
* Specify position independent mode building properly, without
  using the historic hack of adding `-fPIC` as a definition.
  This makes the build system more portable.
* Only detect C++ (and not C) to slightly speed up configuring.
* Specify C++11 mode using modern CMake idioms.
* Fix some whitespace issues.

OGLCompilersDLL/CMakeLists.txt

@@ -1,11 +1,11 @@
 set(SOURCES InitializeDll.cpp InitializeDll.h)
 
 add_library(OGLCompiler STATIC ${SOURCES})
-set_property(TARGET OGLCompiler PROPERTY FOLDER glslang)
+set_property(TARGET OGLCompiler PROPERTY FOLDER glslang POSITION_INDEPENDENT_CODE ON)
 
 if(WIN32)
     source_group("Source" FILES ${SOURCES})
 endif(WIN32)
 
-install(TARGETS OGLCompiler 
-        ARCHIVE DESTINATION lib)
+install(TARGETS OGLCompiler
+        ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR})