Remove Wundef warnings for specification macros

This patch adds a file posix-conf-vars.list that is used to generate
macros to determine if a macro is defined as set, unset or not
defined.  gen-posix-conf-vars.awk processes this file and generates a
header (posix-conf-vars-def.h) with these macros.  A new header
posix-conf-vars.h includes this generated header and defines accessor
macros for the generated macros.

Tested on x86_64.

	* posix/Makefile (before-compile): Add posix-conf-vars-def.h.
	($(objpfx)posix-conf-vars-def.h): New target.
	* posix/posix-conf-vars.list: New file.
	* posix/posix-conf-vars.h: New file.
	* posix/confstr.c: Include posix-conf-vars.h.
	(confstr): Use CONF_IS_* macros.
	* posix/posix-envs.def: Include posix-conf-vars.h.  Use
	CONF_IS_* macros.
	* scripts/gen-posix-conf-vars.awk: New file.

1 files changed, 22 insertions, 0 deletions

diff --git a/posix/posix-conf-vars.list b/posix/posix-conf-vars.list
new file mode 100644
index 0000000000..8f308c2166
--- /dev/null
+++ b/posix/posix-conf-vars.list
@@ -0,0 +1,22 @@
+# Configuration variables identified by getconf.  The heading of each section
+# is of the format TYPE PREFIX with the opening curly brace on the same line.
+# TYPE can either be SYSCONF, PATHCONF, CONFSTR or SPEC.  Variable names are
+# put one on each line with a curly brace on its own line ending the section.
+
+SPEC POSIX {
+  V6_ILP32_OFF32
+  V6_ILP32_OFFBIG
+  V6_LP64_OFF64
+  V6_LPBIG_OFFBIG
+  V7_ILP32_OFF32
+  V7_ILP32_OFFBIG
+  V7_LP64_OFF64
+  V7_LPBIG_OFFBIG
+}
+
+SPEC XBS5 {
+  ILP32_OFF32
+  ILP32_OFFBIG
+  LP64_OFF64
+  LPBIG_OFFBIG
+}