Fix missing MinGW import library prefix

Fixes #657.

README.md

@@ -77,6 +77,7 @@ used by the tests and examples and are not required to build the library.
  - [Win32] Added support for Windows 8.1 per-monitor DPI
  - [Win32] Bugfix: Window creation would segfault if video mode setting required
                    the system to be restarted
+ - [Win32] Bugfix: MinGW import library lacked the `lib` prefix
  - [Cocoa] Removed support for OS X 10.6
  - [Cocoa] Bugfix: Full screen windows on secondary monitors were mispositioned
  - [X11] Bugfix: Monitor connection and disconnection events were not reported

src/CMakeLists.txt

@@ -68,7 +68,7 @@ set_target_properties(glfw PROPERTIES
 if (BUILD_SHARED_LIBS)
     if (WIN32)
         # The GLFW DLL needs a special compile-time macro and import library name
-        set_target_properties(glfw PROPERTIES PREFIX "" IMPORT_PREFIX "")
+        set_target_properties(glfw PROPERTIES PREFIX "")
 
         if (MINGW)
             set_target_properties(glfw PROPERTIES IMPORT_SUFFIX "dll.a")