egl/x11: avoid using freed memory if dri2 init fails

egl/x11: avoid using freed memory if dri2 init fails

Found with valgrind:

==4841== Invalid read of size 4
==4841==    at 0x56BDC80: dri2_initialize (egl_dri2.c:783)
==4841==    by 0x56BAFE5: _eglMatchAndInitialize (egldriver.c:261)
==4841==    by 0x56BB15E: _eglMatchDriver (egldriver.c:295)
==4841==    by 0x56B58C9: eglInitialize (eglapi.c:480)
==4841==    by 0x4F537DC: _glfwInitEGL (in /usr/lib64/libglfw.so.3.2)
==4841==    by 0x4F4BEFB: _glfwPlatformInit (in /usr/lib64/libglfw.so.3.2)
==4841==    by 0x4F46F40: glfwInit (in /usr/lib64/libglfw.so.3.2)
==4841==    by 0x402E59: main
==4841==  Address 0x6a05824 is 148 bytes inside a block of size 480 free'd
==4841==    at 0x4C2B680: free (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==4841==    by 0x56C2AAE: dri2_initialize_x11_swrast (platform_x11.c:1233)
==4841==    by 0x56C2AAE: dri2_initialize_x11 (platform_x11.c:1493)
==4841==    by 0x56BDCEB: dri2_initialize (egl_dri2.c:805)
==4841==    by 0x56BAFAF: _eglMatchAndInitialize (egldriver.c:261)
==4841==    by 0x56BB0C9: _eglMatchDriver (egldriver.c:292)
==4841==    by 0x56B58C9: eglInitialize (eglapi.c:480)
==4841==    by 0x4F537DC: _glfwInitEGL (in /usr/lib64/libglfw.so.3.2)
==4841==    by 0x4F4BEFB: _glfwPlatformInit (in /usr/lib64/libglfw.so.3.2)
==4841==    by 0x4F46F40: glfwInit (in /usr/lib64/libglfw.so.3.2)
==4841==    by 0x402E59: main
==4841==  Block was alloc'd at
==4841==    at 0x4C2A868: calloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==4841==    by 0x56C2A47: dri2_initialize_x11_swrast (platform_x11.c:1171)
==4841==    by 0x56C2A47: dri2_initialize_x11 (platform_x11.c:1493)
==4841==    by 0x56BDCEB: dri2_initialize (egl_dri2.c:805)
==4841==    by 0x56BAFAF: _eglMatchAndInitialize (egldriver.c:261)
==4841==    by 0x56BB0C9: _eglMatchDriver (egldriver.c:292)
==4841==    by 0x56B58C9: eglInitialize (eglapi.c:480)
==4841==    by 0x4F537DC: _glfwInitEGL (in /usr/lib64/libglfw.so.3.2)
==4841==    by 0x4F4BEFB: _glfwPlatformInit (in /usr/lib64/libglfw.so.3.2)
==4841==    by 0x4F46F40: glfwInit (in /usr/lib64/libglfw.so.3.2)
==4841==    by 0x402E59: main

Signed-off-by: Jan Ziak (http://atom-symbol.net) <0xe2.0x9a.0x9b@gmail.com>
Fixes: 9ee683f877 (egl/dri2: Add reference count for dri2_egl_display)
Cc: "12.0" <mesa-stable@lists.freedesktop.org>
Reviewed-by: Nicolas Boichat <drinkcat@chromium.org>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>