Remove some legacy declarations from <math.h>.

These are still needed for backwards compatibility with code built by old
versions of the NDK, but we don't need to pollute the headers with them.

Also lose the hand-written code for these. The compiler-generated code
is either the same or better, and no new code is calling these functions
anyway.

Bug: N/A
Test: ran tests
Change-Id: Ib01ad9805034433e0105aec882608cc8e6526f78
diff --git a/benchmarks/math_benchmark.cpp b/benchmarks/math_benchmark.cpp
index 7b9a283..4d9d3cb 100644
--- a/benchmarks/math_benchmark.cpp
+++ b/benchmarks/math_benchmark.cpp
@@ -69,16 +69,11 @@
 }
 BIONIC_BENCHMARK(BM_math_isfinite_macro);
 
-#if defined(__BIONIC__)
-#define test_isfinite __isfinite
-#else
-#define test_isfinite __finite
-#endif
 static void BM_math_isfinite(benchmark::State& state) {
   d = 0.0;
   v = values[state.range(0)];
   while (state.KeepRunning()) {
-    d += test_isfinite(v);
+    d += isfinite(v);
   }
   SetLabel(state);
 }
@@ -134,17 +129,15 @@
 }
 BIONIC_BENCHMARK(BM_math_isnormal_macro);
 
-#if defined(__BIONIC__)
 static void BM_math_isnormal(benchmark::State& state) {
   d = 0.0;
   v = values[state.range(0)];
   while (state.KeepRunning()) {
-    d += (__isnormal)(v);
+    d += isnormal(v);
   }
   SetLabel(state);
 }
 BIONIC_BENCHMARK(BM_math_isnormal);
-#endif
 
 static void BM_math_sin_fast(benchmark::State& state) {
   d = 1.0;
@@ -202,7 +195,7 @@
   d = 0.0;
   v = values[state.range(0)];
   while (state.KeepRunning()) {
-    d += (__signbit)(v);
+    d += signbit(v);
   }
   SetLabel(state);
 }