Platform: comment cleanup.

What does "window context" mean anyway?

src/Magnum/Platform/CMakeLists.txt

@@ -444,7 +444,7 @@ endif()
 if(NEED_EGLCONTEXTHANDLER)
     find_package(EGL)
     if(NOT EGL_FOUND)
-        message(FATAL_ERROR "EGL library, required by some window contexts, was not found. Set WITH_*EGL*APPLICATION to OFF to skip building them.")
+        message(FATAL_ERROR "EGL library, required by some contexts, was not found. Set WITH_*EGL*APPLICATION to OFF to skip building them.")
     endif()
 
     include_directories(${EGL_INCLUDE_DIR})
@@ -520,7 +520,7 @@ endif()
 if(NEED_EGLCONTEXT OR WITH_EGLCONTEXT)
     find_package(EGL)
     if(NOT EGL_FOUND)
-        message(FATAL_ERROR "EGL library, required by some window contexts, was not found. Set WITH_*APPLICATION and/or WITH_EGLCONTEXT to OFF to skip building them.")
+        message(FATAL_ERROR "EGL library, required by some contexts, was not found. Set WITH_*APPLICATION and/or WITH_EGLCONTEXT to OFF to skip building them.")
     endif()
 
     include_directories(${EGL_INCLUDE_DIR})