Revert "res_config_odbc: Preserve empty strings returned by the database"

This reverts commit a3a2fbaec6.

Reason for revert: There is a lot of code that relies on the broken
behavior that this fixes.

Change-Id: I410c395a0168acbdaf89e616e3cb5e1312d190cb

res/res_config_odbc.c

@@ -305,7 +305,7 @@ static struct ast_variable *realtime_odbc(const char *database, const char *tabl
 		} else {
 			while (stringp) {
 				chunk = strsep(&stringp, ";");
-				if (!strcmp(chunk, " ") || !ast_strlen_zero(ast_strip(chunk))) {
+				if (!ast_strlen_zero(ast_strip(chunk))) {
 					if (strchr(chunk, '^')) {
 						decode_chunk(chunk);
 					}