egl/main: fix EGL_KHR_get_all_proc_addresses

egl/main: fix EGL_KHR_get_all_proc_addresses

The extension requires that the address of the core functions should be
available via eglGetProcAddress. Currently the list is guarded by
_EGL_GET_CORE_ADDRESSES, which was only set for the scons (windows)
build.

Unconditionally enable it for all the builds (automake, android and
haiku) considering that the extension is not platform specific and is
always enabled.

v2: Drop the _EGL_GET_CORE_ADDRESSES macro altogether.

Cc: mesa-stable@lists.freedesktop.org
Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>