Use __RENAME for long double functions.

We can cut a lot of stuff out of the NDK's libandroid_support with this,
and reduce unnecessary relocations for all LP32 code. LP64 code should
be unaffected.

Bug: https://issuetracker.google.com/64450768
Bug: https://github.com/android-ndk/ndk/issues/507
Test: ran tests, plus manual readelf on the _test.o files
Change-Id: I3de6015921195304ea9c829ef31665cd34664066
diff --git a/libm/Android.bp b/libm/Android.bp
index e5cb029..bf86264 100644
--- a/libm/Android.bp
+++ b/libm/Android.bp
@@ -506,6 +506,7 @@
     ],
 
     cflags: [
+        "-D__BIONIC_LP32_USE_LONG_DOUBLE",
         "-D__BIONIC_NO_MATH_INLINES",
         "-D_BSD_SOURCE",
         "-DFLT_EVAL_METHOD=0",