Export double precision implementations

This patch exports exp, exp2, log, log2, and pow.  All mathtests pass
on x86_64, x86, arm64, and arm.

Bug: N/A
Test: Ran tests.

Change-Id: I78157bfa030fca001fb7535d49551416883cd6fe
diff --git a/Android.bp b/Android.bp
index d533695..e8ded12 100755
--- a/Android.bp
+++ b/Android.bp
@@ -12,14 +12,24 @@
     ],
     srcs: [
         "math/cosf.c",
+        "math/exp2.c",
         "math/exp2f.c",
         "math/exp2f_data.c",
+        "math/exp.c",
+        "math/exp_data.c",
         "math/expf.c",
+        "math/log2.c",
+        "math/log2_data.c",
         "math/log2f.c",
         "math/log2f_data.c",
+        "math/log.c",
+        "math/log_data.c",
         "math/logf.c",
         "math/logf_data.c",
+        "math/math_err.c",
         "math/math_errf.c",
+        "math/pow.c",
+        "math/pow_log_data.c",
         "math/powf.c",
         "math/powf_log2_data.c",
         "math/sincosf.c",