Add sincos() and sincosf() implementation.

This is a GLibc-compatibility patch required to simplify our
upcoming toolchain work/porting.

Change-Id: I615a20a449763f86b6e2b0e4f5ab43fb029ceb6d
diff --git a/libm/Android.mk b/libm/Android.mk
index fa73aff..28e8f33 100644
--- a/libm/Android.mk
+++ b/libm/Android.mk
@@ -3,6 +3,7 @@
 libm_common_src_files:= \
 	isinf.c  \
 	fpclassify.c \
+	sincos.c \
 	bsdsrc/b_exp.c \
 	bsdsrc/b_log.c \
 	bsdsrc/b_tgamma.c \