Make visible symbols required by xorg modules.

This patch exports all symbols required by the compilable
(in a x86 linux computer) xorg/driver/* modules.
  Still missing symbols worth mentioning are:

sunleo
	miFindMaxBand no longer available

intel	(uxa/uxa-accel.c)
	fbShmPutImage no longer available (and should have been static)

mga
	MGAGetClientPointer (should come from matrox's libhal)

  This is not a definitive "visibility" patch, as all it does is to
export missing symbols, but the modules that current don't compile,
may require more symbols once fixed, and third party drivers should
also require more symbols exported.
  A "definitive" patch should export symbols defined in the sdk.

exa/exa_offscreen.c

@@ -164,7 +164,7 @@ exaFindAreaToEvict(ExaScreenPrivPtr pExaScr, int size, int align)
  * requested version 2.1 or newer behavior.  In that case, the save callback is
  * still called.
  */
-ExaOffscreenArea *
+_X_EXPORT ExaOffscreenArea *
 exaOffscreenAlloc (ScreenPtr pScreen, int size, int align,
                    Bool locked,
                    ExaOffscreenSaveProc save,
@@ -365,7 +365,7 @@ ExaOffscreenSwapIn (ScreenPtr pScreen)
  * many drivers that could otherwise handle the lack of FB access while
  * swapped out.
  */
-void
+_X_EXPORT void
 exaEnableDisableFBAccess (int index, Bool enable)
 {
     ScreenPtr pScreen = screenInfo.screens[index];
@@ -412,7 +412,7 @@ ExaOffscreenMerge (ExaOffscreenArea *area)
  * @return pointer to the newly freed area. This behavior should not be relied
  * on.
  */
-ExaOffscreenArea *
+_X_EXPORT ExaOffscreenArea *
 exaOffscreenFree (ScreenPtr pScreen, ExaOffscreenArea *area)
 {
     ExaScreenPriv(pScreen);
@@ -453,7 +453,7 @@ exaOffscreenFree (ScreenPtr pScreen, ExaOffscreenArea *area)
     return area;
 }
 
-void
+_X_EXPORT void
 ExaOffscreenMarkUsed (PixmapPtr pPixmap)
 {
     ExaPixmapPriv (pPixmap);