Add -Wl,--no-fatal-warnings to x86 build

libart.so has text relocations. When -Wl,--fatal-warnings is added
to the global LDFLAGS, these text relocations will become a compile
error.

This is a short term workaround until the text relocations can be
fixed properly.

Bug: 11358761
Bug: 11353056

(cherry picked from commit 59fe2a68)

Change-Id: Id604bdec5d4fdf2606b9970cf65b6a358b9a673a