[Patch, Fortran] PR32980 - Add GAMMA and LGAMMA intrinsics

[Tobias Schlüter]

Tobias Burnus wrote:
> :ADDPATCH fortran:
> 
> This patch adds:
> 
> a) The gamma function as vendor intrinsic GAMMA with the specific names
> GAMMA and DGAMMA. (Only) "GAMMA" is also part of the current Fortran
> 2008 draft.
> 
> b) The logarithm of the absolute value of the Gamma function as vendor
> intrinsic LGAMMA with the specific names AGAMA and DGAMA. The Fortran
> 2008 draft has this function under the name LOG_GAMMA.
> 
> While LGAMMA is compatible to LOG_GAMMA, I did not add the F2008/draft
> version. Anyone thinks that I should?
> 
> 
> Note: The functions tgamma (t = true) and lgamma are part of C99.
> 
> Regression tested on x86-64/Linux. Ok for the trunk?

I'm worried that this will lead to surprising results for people that 
have their own GAMMA functions defined.  Maybe a new std class is 
appropriate?  What's the opposite of "legacy"?  Maybe "incompatible", as 
in "even incompatible extensions"?

- Tobi