Add tgamma1pm1 speed test.

Suppress some more gcc warnings: in particular make sure that our C99 functions have the same throw specification as the functions in math.h.

[SVN r59129]

libs/math

@@ -1 +1 @@
-Subproject commit 1a5044497dbfa7fca9964ff81d39c66cd1e5a52b
+Subproject commit ea3573355024fab9baa3505b7ef72416a913b9f5