postgresql: add version output to pg_config

Some external packages call pg_config to determine the installed PostgreSQL
version. Add this output to Buildroots own pg_config, so these packages
correctly compile.

Signed-off-by: Adam Duskett <aduskett@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/postgresql/pg_config

@@ -14,6 +14,9 @@ case "$1" in
   --libdir)
 	echo "$prefix/lib"
 	;;
+  --version)
+	echo "PostgreSQL @POSTGRESQL_VERSION@"
+	;;
   *)
-	echo "Usage: $0 {--includedir|--libdir}"
+	echo "Usage: $0 {--includedir|--libdir|--version}"
 esac

package/postgresql/postgresql.mk

@@ -84,6 +84,7 @@ POSTGRESQL_POST_INSTALL_TARGET_HOOKS += POSTGRESQL_INSTALL_TARGET_FIXUP
 define POSTGRESQL_INSTALL_CUSTOM_PG_CONFIG
 	$(INSTALL) -m 0755 -D package/postgresql/pg_config \
 		$(STAGING_DIR)/usr/bin/pg_config
+	$(SED) "s|@POSTGRESQL_VERSION@|$(POSTGRESQL_VERSION)|g" $(STAGING_DIR)/usr/bin/pg_config
 endef
 
 POSTGRESQL_POST_INSTALL_STAGING_HOOKS += POSTGRESQL_INSTALL_CUSTOM_PG_CONFIG