kconfig: display an error message when aborting

If the Kconfig option causes an open() failure (like one that starts with
an underscore), there should be an error message shown since we're going
to be exiting with an error code.  Otherwise, the reason for the failure
can really only be diagnosed with strace or something similar.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

scripts/kconfig/confdata.c

diff --git a/scripts/kconfig/confdata.c b/scripts/kconfig/confdata.c
index 59b667c..7732dec 100644
--- a/scripts/kconfig/confdata.c
+++ b/scripts/kconfig/confdata.c
@@ -875,6 +875,8 @@
 		fd = open(path, O_WRONLY | O_CREAT | O_TRUNC, 0644);
 		if (fd == -1) {
 			if (errno != ENOENT) {
+				conf_warning("sym '%s' with path '%s': %s",
+					     sym->name, path, strerror(errno));
 				res = 1;
 				break;
 			}