Add -DFLT_EVAL_METHOD=0 and -ffp-contract=fast

This patch adds both FLT_EVAL_METHOD set to 0 (to avoid double_t
being evaluated as long double) and -ffp-contract=fast to clang
can use FMA on targets which supports it.

The -ffp-contract=fast is specially required for aarch64 and the
optimized implementations are targeting explicit architectures
with contracted floating-point operations.

Bug: N/A
Test: ran tests

Change-Id: I4719e909e84435f8017a3d5a6dca87040b9d8aa5
diff --git a/Android.bp b/Android.bp
index bb77bfb..1e39081 100755
--- a/Android.bp
+++ b/Android.bp
@@ -6,6 +6,8 @@
         "-O2",
         "-DWANT_ROUNDING=0",
         "-DWANT_ERRNO=0",
+        "-DFLT_EVAL_METHOD=0",
+        "-ffp-contract=fast",
     ],
     srcs: [
         "math/*.c",