php: don't use DOWNLOAD macro

php.net only offers downloads though a strange php script with the file name
embedded in the *MIDDLE* of the URL, which isn't compatible with the DOWNLOAD
macro. Fix it by reverting php.mk hunk of r24689 to go back to $(WGET).

This ofcourse means that the primary site / fallback mirror stuff isn't used.

package/php/php.mk

@@ -126,7 +126,7 @@ endif
 endif
 
 $(DL_DIR)/$(PHP_SOURCE):
-	 $(call DOWNLOAD,$(PHP_SITE))
+	$(WGET) -P $(DL_DIR) $(PHP_SITE)
 
 php-source: $(DL_DIR)/$(PHP_SOURCE)