opkg: do not add blank "Provides:" fields to package metadata

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@39039 3c298f89-4303-0410-b956-a3cf2f4a3e73

package/system/opkg/patches/090-suppress-blank-provides-field.patch

+--- a/libopkg/pkg.c
++++ b/libopkg/pkg.c
+@@ -731,7 +731,7 @@ pkg_formatted_field(FILE *fp, pkg_t *pkg
+ 	  } else if (strcasecmp(field, "Priority") == 0) {
+                fprintf(fp, "Priority: %s\n", pkg->priority);
+ 	  } else if (strcasecmp(field, "Provides") == 0) {
+-	       if (pkg->provides_count) {
++	       if (pkg->provides_count > 1) {
+                   fprintf(fp, "Provides:");
+ 		  for(i = 1; i < pkg->provides_count; i++) {
+                       fprintf(fp, "%s %s", i == 1 ? "" : ",",