egl: Cleanup _EGLDisplay initialization.

Reorder/rename and document the fields that should be set by the driver during
initialization.  Drop the major/minor arguments from drv->API.Initialize.

src/egl/main/egldisplay.h

@@ -74,8 +74,6 @@ struct _egl_extensions
 
    EGLBoolean NOK_swap_region;
    EGLBoolean NOK_texture_from_pixmap;
-
-   char String[_EGL_MAX_EXTENSIONS_LEN];
 };
 
 
@@ -86,21 +84,23 @@ struct _egl_display
 
    _EGLMutex Mutex;
 
-   _EGLPlatformType Platform;
-   void *PlatformDisplay;
+   _EGLPlatformType Platform; /**< The type of the platform display */
+   void *PlatformDisplay;     /**< A pointer to the platform display */
 
-   EGLBoolean Initialized; /**< True if the display is initialized */
-   _EGLDriver *Driver;
-   void *DriverData; /* private to driver */
+   _EGLDriver *Driver;        /**< Matched driver of the display */
+   EGLBoolean Initialized;    /**< True if the display is initialized */
 
-   int APImajor, APIminor; /**< as returned by eglInitialize() */
-   char Version[1000];     /**< initialized from APImajor/minor, DriverName */
+   /* these fields are set by the driver during init */
+   void *DriverData;          /**< Driver private data */
+   EGLint VersionMajor;       /**< EGL major version */
+   EGLint VersionMinor;       /**< EGL minor version */
+   EGLint ClientAPIs;         /**< Bitmask of APIs supported (EGL_xxx_BIT) */
+   _EGLExtensions Extensions; /**< Extensions supported */
 
-   /** Bitmask of supported APIs (EGL_xx_BIT) set by the driver during init */
-   EGLint ClientAPIsMask;
-   char ClientAPIs[1000];   /**< updated by eglQueryString */
-
-   _EGLExtensions Extensions;
+   /* these fields are derived from above */
+   char VersionString[1000];                       /**< EGL_VERSION */
+   char ClientAPIsString[1000];                    /**< EGL_CLIENT_APIS */
+   char ExtensionsString[_EGL_MAX_EXTENSIONS_LEN]; /**< EGL_EXTENSIONS */
 
    _EGLArray *Screens;
    _EGLArray *Configs;