*printf-posix: Detect a bug on Solaris 10/x86.

*printf-posix: Detect a bug on Solaris 10/x86.

* m4/printf.m4 (gl_PRINTF_PRECISION): Detect crash with large precision
for floating-point output.
* tests/test-vasnprintf-posix.c (test_function): Test precision with %f
directive.
* tests/test-snprintf-posix.h (test_function): Likewise.
* tests/test-sprintf-posix.h (test_function): Likewise.
* tests/test-vasprintf-posix.c (test_function): Likewise.
* doc/posix-functions/fprintf.texi: Mention Solaris/x86 bug.
* doc/posix-functions/printf.texi: Likewise.
* doc/posix-functions/snprintf.texi: Likewise.
* doc/posix-functions/sprintf.texi: Likewise.
* doc/posix-functions/vfprintf.texi: Likewise.
* doc/posix-functions/vprintf.texi: Likewise.
* doc/posix-functions/vsnprintf.texi: Likewise.
* doc/posix-functions/vsprintf.texi: Likewise.
* doc/glibc-functions/obstack_printf.texi: Likewise.
* doc/glibc-functions/obstack_vprintf.texi: Likewise.