Update to FreeBSD libm r336665.

This reverts commit 253a8306316cedfd6fd3e3a169fbffe4cac04035 and moves
us forward to a revision that contains fixes for the problem with the
previous attempt.

This also makes sincos(3)/sincosf(3)/sincosl(3) available to `_BSD_SOURCE`
as well as `_GNU_SOURCE`.

The new FreeBSD libm code requires the FreeBSD `__CONCAT` macro, and all
our existing callers are FreeBSD too, so update that.

There's also an assumption that <complex.h> drags in <math.h> which isn't
true for us, so work around that with `-include` in the makefile. This
then causes clang to recognize a bug -- returning from a void function --
in our fake (LP32) sincosl(3), so fix that too.

Bug: http://b/111710419
Change-Id: I84703ad844f8afde6ec6b11604ab3c096ccb62c3
Test: ran tests
diff --git a/libm/upstream-freebsd/lib/msun/src/e_j1f.c b/libm/upstream-freebsd/lib/msun/src/e_j1f.c
index 0cca823..3abe201 100644
--- a/libm/upstream-freebsd/lib/msun/src/e_j1f.c
+++ b/libm/upstream-freebsd/lib/msun/src/e_j1f.c
@@ -14,7 +14,7 @@
  */
 
 #include <sys/cdefs.h>
-__FBSDID("$FreeBSD: head/lib/msun/src/e_j1f.c 283032 2015-05-17 16:27:06Z kargl $");
+__FBSDID("$FreeBSD: head/lib/msun/src/e_j1f.c 336089 2018-07-08 16:26:13Z markj $");
 
 /*
  * See e_j1.c for complete comments.
@@ -32,7 +32,7 @@
 one	= 1.0,
 invsqrtpi=  5.6418961287e-01, /* 0x3f106ebb */
 tpi      =  6.3661974669e-01, /* 0x3f22f983 */
-	/* R0/S0 on [0,2] */
+/* R0/S0 on [0,2] */
 r00  = -6.2500000000e-02, /* 0xbd800000 */
 r01  =  1.4070566976e-03, /* 0x3ab86cfd */
 r02  = -1.5995563444e-05, /* 0xb7862e36 */