nir: check NIR_SKIP to skip passes by name

Passes' function names, separated by comma, listed in NIR_SKIP
environment variable will be skipped in debug mode.  The mechanism is
hooked into the _PASS macro, like NIR_PRINT.

The extra macro NIR_SKIP is available as a developer convenience, to
skip at pointer other than the passes entry points.

v2: Fix typo in NIR_SKIP macro. (Bas)

Reviewed-by: Alejandro Piñeiro <apinheiro@igalia.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>

src/util/debug.c

@@ -53,6 +53,20 @@ parse_debug_string(const char *debug,
    return flag;
 }
 
+bool
+comma_separated_list_contains(const char *list, const char *s)
+{
+   assert(list);
+   const size_t len = strlen(s);
+
+   for (unsigned n; n = strcspn(list, ","), *list; list += MAX2(1, n)) {
+      if (n == len && !strncmp(list, s, n))
+         return true;
+   }
+
+   return false;
+}
+
 /**
  * Reads an environment variable and interprets its value as a boolean.
  *