mesa/main: factor out one-time-init into a helper

This will make the next commit a bit cleaner.

Reviewed-by: Kristian H. Kristensen <hoegsberg@google.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5879>

src/mesa/main/context.c

@@ -340,14 +340,6 @@ _mesa_destroy_visual( struct gl_config *vis )
 /*@{*/
 
 
-/**
- * One-time initialization mutex lock.
- *
- * \sa Used by one_time_init().
- */
-mtx_t OneTimeLock = _MTX_INITIALIZER_NP;
-
-
 /**
  * Calls all the various one-time-fini functions in Mesa
  */
@@ -360,23 +352,12 @@ one_time_fini(void)
 }
 
 /**
- * Calls all the various one-time-init functions in Mesa.
- *
- * While holding a global mutex lock, calls several initialization functions,
- * and sets the glapi callbacks if the \c MESA_DEBUG environment variable is
- * defined.
- *
- * \sa _math_init().
+ * Calls all the various one-time-init functions in Mesa
  */
-void
-_mesa_initialize(void)
+
+static void
+one_time_init(void)
 {
-   static bool initialized;
-
-   mtx_lock(&OneTimeLock);
-
-   /* truly one-time init */
-   if (!initialized) {
    GLuint i;
 
    STATIC_ASSERT(sizeof(GLbyte) == 1);
@@ -412,6 +393,34 @@ _mesa_initialize(void)
    _mesa_init_remap_table();
 }
 
+/**
+ * One-time initialization mutex lock.
+ *
+ * \sa Used by _mesa_initialize().
+ */
+mtx_t OneTimeLock = _MTX_INITIALIZER_NP;
+
+
+/**
+ * Calls all the various one-time-init functions in Mesa.
+ *
+ * While holding a global mutex lock, calls several initialization functions,
+ * and sets the glapi callbacks if the \c MESA_DEBUG environment variable is
+ * defined.
+ *
+ * \sa _math_init().
+ */
+void
+_mesa_initialize(void)
+{
+   static bool initialized;
+
+   mtx_lock(&OneTimeLock);
+
+   /* truly one-time init */
+   if (!initialized)
+      one_time_init();
+
    initialized = true;
 
    mtx_unlock(&OneTimeLock);