Issue with gl_WCHAR_H on z/OS

[Steve Goetze]

This test is intended to check for <wchar.h> issues related to gcc and the
transition from __inline to gnu_inline.  It is located in "m4/wchar.m4" in
m4-1.4.14.  When compiling on z/OS with the IBM xlc compiler, the test fails
for an unrelated reason:  When running the compiler on z/OS with the
-qxplink option (this is preferred), the test itself compiles two object
files that are linked together.  Because the source file names for both
files is the traditional "conftest.c", they cause identical CSECT names to
be generated, resulting in a link error.  There are several ways to work
around this issue - I'd appreciate any advice on the best approach.

1.) Skip this test on z/OS, or if the compiler is not gcc.  This seems like
the simplest thing to do, and makes sense given that the test is
specifically for gcc behavior
2.) On z/OS specify the xlc CFLAG -qnocsect during configure / make.  This
will enable the build, but could introduce serviceablility / support issues
3.) Don't configure with -qxplink, but specify during make.

Thanks,
--Steve Goetze