scons: Updates for targets/egl-static.

Update SConscripts to re-enable or add support for EGL on windows and
x11 platforms respectively.  targets/egl-gdi is replaced by
targets/egl-static, where "-static" means pipe drivers and state
trackers are linked to statically by egl_gallium, and egl_gallium is a
built-in driver of libEGL.  There is no more egl_gallium.dll on Windows.

src/gallium/SConscript

@@ -55,6 +55,7 @@ SConscript('winsys/sw/null/SConscript')
 SConscript('state_trackers/python/SConscript')
 if env['platform'] != 'embedded':
     SConscript('state_trackers/vega/SConscript')
+    SConscript('state_trackers/egl/SConscript')
 
     if env['x11']:
         SConscript('state_trackers/glx/xlib/SConscript')
@@ -66,10 +67,7 @@ if env['platform'] != 'embedded':
         SConscript('state_trackers/xorg/SConscript')
 
 if env['platform'] == 'windows':
-    SConscript([
-        'state_trackers/egl/SConscript',
-        'state_trackers/wgl/SConscript',
-    ])
+    SConscript('state_trackers/wgl/SConscript')
 
 #
 # Winsys
@@ -85,6 +83,11 @@ SConscript([
     'targets/graw-null/SConscript',
 ])
 
+if env['platform'] != 'embedded':
+    SConscript([
+        'targets/egl-static/SConscript'
+    ])
+
 if env['x11']:
     SConscript([
         'targets/graw-xlib/SConscript',
@@ -95,7 +98,6 @@ if env['platform'] == 'windows':
     SConscript([
         'targets/graw-gdi/SConscript',
         'targets/libgl-gdi/SConscript',
-        #'egl-gdi/SConscript',
     ])
 
 if env['dri']: