Fixed crash if initialization of EGL failed but was tried again later.

The internal function SDL_EGL_LoadLibrary() did not delete and remove a mostly
uninitialized data structure if loading the library first failed. A later try to
use EGL then skipped initialization and assumed it was previously successful
because the data structure now already existed. This led to at least one crash
in the internal function SDL_EGL_ChooseConfig() because a NULL pointer was
dereferenced to make a call to eglBindAPI().

docs/README-cmake.md

@@ -0,0 +1,32 @@
+CMake
+================================================================================
+(www.cmake.org)
+
+SDL's build system was traditionally based on autotools. Over time, this
+approach has suffered from several issues across the different supported 
+platforms.
+To solve these problems, a new build system based on CMake is under development.
+It works in parallel to the legacy system, so users can experiment with it
+without complication.
+While still experimental, the build system should be usable on the following
+platforms:
+
+* FreeBSD
+* Linux
+* VS.NET 2010
+* MinGW and Msys
+* OS X with support for XCode
+
+
+================================================================================
+Usage
+================================================================================
+
+Assuming the source for SDL is located at ~/sdl
+
+    cd ~
+    mkdir build
+    cd build
+    cmake ../sdl
+
+This will build the static and dynamic versions of SDL in the ~/build directory.