1.0.42.20: use platform-dependent CFLAGS consistently in tests

1.0.42.20: use platform-dependent CFLAGS consistently in tests

 Patch by Josh Elsasser, lp#615499.

 In his words:

 "Attached is a patch which moves all the duplicated, out-of-sync C
 compiler flag selection in the tests into a single wrapper script.
 When passed a flag like -sbcl-pic or -sbcl-shared, the script will
 decided if -fPIC or -shared/-bundle is needed based on SOFTWARE-TYPE
 and MACHINE-TYPE which SBCL has passed in the environment.

 I tested this on several x86 OSes and a couple PowerPC, as well as
 SunOS on SPARC and OpenBSD on x86-64. For the -sbcl-pic case I have
 verified that -fPIC is needed on OpenBSD-PowerPC, OpenBSD-X86-64,
 SunOS-SPARC and SunOS-X86; the other cases are guesses based on the
 existing reader conditionals. It is not needed on Darwin or Linux on
 PowerPC, or on any x86 OSes I tested aside from SunOS.

 I haven't verified that -arch x86_64 is actually needed on
 Darwin-X86-64, or that something like -m64 isn't needed on other
 X86-64 OSes (aside from OpenBSD)."