This is a bit more consistent with the naming of the other header files
(openlibm_complex.h and openlibm_fenv.h). Re-add an openlibm.h header
that includes all of the public headers as a shorthand.
Fix up all of the source files to include <openlibm_math.h> instead of
<openlibm.h>. While there, fix ordering of the includes.
The global signgam variable is only part of the X/Open System
Interfaces. It is not part of the POSIX base definitions nor the C
standard.
I'd rather have it disabled for my specific use-case, so introduce a new
compilation flag that we can use to disable it.
Put external headers before internal ones. While there, replace a lot of
occurences of "openlibm.h" with <openlibm.h>. It should be thought of as
an external header, as it is installed along with the library.
We already provide lgammaf_r() and lgamma_r(). It's not hard to also add
lgammal_r(), for consistency.
I am currently working on porting openlibm to an environment where
global state, and thus signgam, is not available. By adding lgammal_r(),
I can trivially disable support for signgam by just patching up
src/e_lgamma{f,,l}.c. That way there is no need to patch up the actual
algorithms.
Keno Fischer