bionic/libm: fix x86 support regression

Support for x86 and MIPS broke due to an incorrect merge conflict
resolution in commit 5015fe9.  Commit d348cd5 repaired MIPS support
but not x86.  This commit repairs the incorrect merge conflict
resolution, bringing back support for x86 (and potential future
architectures).

Change-Id: I8994d653e5a2f79c9bfacb1c87159c8cdd4f81a7

Conflicts:
	libm/Android.mk

Signed-off-by: Paul Beeler <sparksco@gmail.com>