Application of patch

	Fortran REAL*16 detection
	http://www.cactuscode.org/old/pipermail/patches/2006-April/000164.html

... a patch that makes Cactus directly detect Fortran support
for a REAL*16 type.

The problem has been that Cactus based CCTK_REAL16 on support for the C type
'long double'.  This would cause it to create Fortran code for REAL*16, a
type which was sometimes not supported.

In particular, on a 64-bit Athlon machine with Gnu 4.1.0, gfortran
defines REAL*8 but not REAL*16, while gcc defines 'long double'.
This caused thorn AEIThorns/Fortran to fail to compile.

This patch causes the configuration to directly compile Fortran code that
features REAL*16, and define CCTK_REAL16 only if that compiles *and* C's
'long double' is supported.

When you make config, you will see a new line about Fortran REAL*16.

I have tested the enclosed patch on
	my laptop with Gnu 4.10 and Intel 9.0 compilers
	64-bit AMD Athlon with same compilers
	POWER4 with IBM XL compilers

BUT NOTE:  I have severe doubts about using REAL*16 on any of these
architectures.  That 16-byte (128-bit) type is not natively supported
on the Xeon, Athlon, or POWER machines.  While some compilers support
such types, calculation is done in software, not on the FPU.


git-svn-id: http://svn.cactuscode.org/flesh/trunk@4314 17b73243-c579-4c4c-a9d2-2d5706c11dac

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