util: move brw_env_var_as_boolean() to util

Kind of a handy function.  And I'll want it available outside of i965
for common nir-pass helpers.

Signed-off-by: Rob Clark <robclark@freedesktop.org>
Reviewed-by: Nicolai Hähnle <nhaehnle@gmail.com>

src/mesa/drivers/dri/i965/intel_debug.c

@@ -103,28 +103,3 @@ brw_process_intel_debug_variable(void)
    uint64_t intel_debug = parse_debug_string(getenv("INTEL_DEBUG"), debug_control);
    (void) p_atomic_cmpxchg(&INTEL_DEBUG, 0, intel_debug);
 }
-
-/**
- * Reads an environment variable and interprets its value as a boolean.
- *
- * Recognizes 0/false/no and 1/true/yes.  Other values result in the default value.
- */
-bool
-brw_env_var_as_boolean(const char *var_name, bool default_value)
-{
-   const char *str = getenv(var_name);
-   if (str == NULL)
-      return default_value;
-
-   if (strcmp(str, "1") == 0 ||
-       strcasecmp(str, "true") == 0 ||
-       strcasecmp(str, "yes") == 0) {
-      return true;
-   } else if (strcmp(str, "0") == 0 ||
-              strcasecmp(str, "false") == 0 ||
-              strcasecmp(str, "no") == 0) {
-      return false;
-   } else {
-      return default_value;
-   }
-}