add _DEFAULT_SOURCE wherever _BSD_SOURCE was used
math: emit less errors for known broken functions
add feature test macros to non-c99 math tests
new test system
math: in lgamma* only check signgam when it's specified
math: add special case test vectors
math: add fenv pragma, relax the error check, simplify util.h
math: add some float f(float,int) and some float f(float,int*) tests