Use the appropriate GLES library name for Windows

Shared libraries on Windows use `.dll` for the extension, not `.so`.

Signed-off-by: Emmanuele Bassi <ebassi@gnome.org>

src/dispatch_common.c

@@ -114,6 +114,10 @@
 #define EGL_LIB "libEGL.so"
 #define GLES1_LIB "libGLESv1_CM.so"
 #define GLES2_LIB "libGLESv2.so"
+#elif defined _WIN32
+#define EGL_LIB "libEGL.dll"
+#define GLES1_LIB "libGLES_CM.dll"
+#define GLES2_LIB "libGLESv2.dll"
 #else
 #define EGL_LIB "libEGL.so.1"
 #define GLES1_LIB "libGLESv1_CM.so.1"