Merge branch 'bugfix/conf_across_mountpoints' into 'master'

Create temp config in the same dir as target



Fixes case where SDK and app are on different mounts



(In our usage of kconfig, dirname is the empty string & basename is the full path to sdkconfig)



Github pull request https://github.com/espressif/esp-idf/pull/151





See merge request !309

tools/kconfig/confdata.c

@@ -771,7 +771,7 @@ int conf_write(const char *name)
 	sprintf(newname, "%s%s", dirname, basename);
 	env = getenv("KCONFIG_OVERWRITECONFIG");
 	if (!env || !*env) {
-		sprintf(tmpname, "%s.tmpconfig.%d", dirname, (int)getpid());
+		sprintf(tmpname, "%s.tmpconfig.%d", newname, (int)getpid());
 		out = fopen(tmpname, "w");
 	} else {
 		*tmpname = 0;