compile warning with ./gnulib-tool --with-tests

[Eric Blake]

Right now, './gnulib-tool --with-tests --test xstrtol' issues this warning when 
run on cygwin 1.5.24:

gcc -DHAVE_CONFIG_H -I. -I../../gltests  -I. -I../../gltests -I.. -
I../../gltests/.. -I../gllib -I../../gltests/../gllib   -g -O2 -MT test-
wchar.o -MD -MP -MF .deps/test-wchar.Tpo -c -o test-wchar.o ../../gltests/test-
wchar.c
In file included from ../../gltests/test-wchar.c:20:
./config.h:155:1: warning: "__STDC_LIMIT_MACROS_TRIGGER" redefined
In file included from ./config.h:4,
                 from ../../gltests/test-wchar.c:20:
./../config.h:147:1: warning: this is the location of the previous definition


Something weird is going on; gnulib-tool created the testdir in such a manner 
that both build/config.h and build/gltests/config.h, with the latter #including 
the former.  And while both files contain similar #defines (for example, both 
did #define HAVE_DECL_IMAXABS 1), it is only the dual listing of 
__STDC_LIMIT_MACROS_TRIGGER that caused gcc 3.4.4 to warn, even though both 
definitions were to the same value.

Is there any reason why gnulib-tool uses AH_TOP([#include "../config.h"]) for 
gltests/configure.ac?  Could this be reworked to have the tests dir share the 
same config.h as the rest of the project, rather than having two files with 
duplicate definitions?

-- 
Eric Blake