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
Change-Id: I886d668a1bd6ed326f6552693d8c38c5d5a6b43d