modules: support ANGLE in FindOpenGLES2/3 and FindEGL CMake modules.

It has lib prefix even on Windows, making it unfindable for CMake.

modules/FindEGL.cmake

@@ -33,7 +33,9 @@
 #
 
 # Library
-find_library(EGL_LIBRARY EGL)
+find_library(EGL_LIBRARY NAMES
+    EGL
+    libEGL) # ANGLE (CMake doesn't search for lib prefix on Windows)
 
 # Include dir
 find_path(EGL_INCLUDE_DIR

modules/FindOpenGLES2.cmake

@@ -37,6 +37,7 @@
 if(NOT CORRADE_TARGET_EMSCRIPTEN)
     find_library(OPENGLES2_LIBRARY NAMES
         GLESv2
+        libGLESv2 # ANGLE (CMake doesn't search for lib prefix on Windows)
         ppapi_gles2) # NaCl
     set(OPENGLES2_LIBRARY_NEEDED OPENGLES2_LIBRARY)
 endif()

modules/FindOpenGLES3.cmake

@@ -40,7 +40,9 @@ if(NOT CORRADE_TARGET_EMSCRIPTEN)
 
         # On some platforms (e.g. desktop emulation with Mesa or NVidia) ES3
         # support is provided in ES2 lib
-        GLESv2)
+        GLESv2
+
+        libGLESv2) # ANGLE (CMake doesn't search for lib prefix on Windows)
     set(OPENGLES3_LIBRARY_NEEDED OPENGLES3_LIBRARY)
 endif()