Resolve "Drop libpcre dependency"

Closes #32 (closed)

inc/lektor/macro.h

@@ -55,6 +55,12 @@
         fprintf(stderr, " ! %s: %s\n", __func__, msg);                  \
         return ret;                                                     \
     }
+#define GOTO_IF(cond, msg, label)                                       \
+    if (cond) {                                                         \
+        fprintf(stderr, " ! %s: %s\n", __func__, msg);                  \
+        goto label;                                                     \
+    }
 
+#define GOTO_UNLESS(cond, msg, label)   GOTO_IF(!(cond), msg, ret)
 #define RETURN_UNLESS(cond, msg, ret)   RETURN_IF(!(cond), msg, ret)
 #define NOTHING                         /* Usefull to return nothing. */