Expose all math *l functions as aliases for the * functions when long double == double

[Justin Hibbits]

On Thu, 27 Dec 2018 14:15:23 -0800
Steve Kargl <sgk at troutmask.apl.washington.edu> wrote:

> On Thu, Dec 27, 2018 at 04:09:37PM -0600, Justin Hibbits wrote:
> > When building editors/calligra on powerpc64 it failed with undefined
> > references to erfl and erfcl.  Some digging it turns out that these
> > functions aren't being exposed as weak symbols in libm on platforms
> > where long double is 64 bits, because LDBL_MANT_DIG is not defined
> > in the files defining these functions.  The attached patch fixes
> > that case.  It's only been compile-tested for powerpc64, but should
> > have no negative impact on any other platform.
> > 
> > - Justin  
> 
> Looks OK to me.
> 

Thanks Steve.  I figured there would be no issue, but since this is
listed in MAINTAINERS, better to avoid a possibility of post-commit
backlash.

- Justin