support: introduce support_sysconfdir_prefix

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

support/Makefile

@@ -231,7 +231,8 @@ CFLAGS-support_paths.c = \
 		-DSBINDIR_PATH=\"$(sbindir)\" \
 		-DSLIBDIR_PATH=\"$(slibdir)\" \
 		-DROOTSBINDIR_PATH=\"$(rootsbindir)\" \
-		-DCOMPLOCALEDIR_PATH=\"$(complocaledir)\"
+		-DCOMPLOCALEDIR_PATH=\"$(complocaledir)\" \
+		-DSYSCONFDIR_PATH=\"$(sysconfdir)\"
 
 # In support_timespec_check_in_range we may be passed a very tight
 # range for which we should produce a correct result for expected

support/support.h

@@ -144,6 +144,8 @@ extern const char support_slibdir_prefix[];
 extern const char support_install_rootsbindir[];
 /* Corresponds to the install's compiled locale directory.  */
 extern const char support_complocaledir_prefix[];
+/* Corresponds to the install's etc/ directory.  */
+extern const char support_sysconfdir_prefix[];
 
 /* Copies the file at the path FROM to TO.  If TO does not exist, it
    is created.  If TO is a regular file, it is truncated before

support/support_paths.c

@@ -92,3 +92,10 @@ const char support_complocaledir_prefix[] = COMPLOCALEDIR_PATH;
 #else
 # error please -DCOMPLOCALEDIR_PATH=something in the Makefile
 #endif
+
+#ifdef SYSCONFDIR_PATH
+/* Corresponds to the install's etc/ directory.  */
+const char support_sysconfdir_prefix[] = SYSCONFDIR_PATH;
+#else
+# error please -DSYSCONFDIR_PATH=something in the Makefile
+#endif