st/xorg: Detect libkms with scons too.

scons/gallium.py

@@ -559,6 +559,7 @@ def generate(env):
     pkg_config_modules(env, 'x11', ['x11', 'xext'])
     pkg_config_modules(env, 'dri', ['libdrm'])
     pkg_config_modules(env, 'xorg', ['xorg-server'])
+    pkg_config_modules(env, 'kms', ['libkms'])
 
     # Custom builders and methods
     env.Tool('custom')

src/gallium/state_trackers/xorg/SConscript

@@ -14,6 +14,9 @@ env.Append(CPPPATH = [
 
 env.ParseConfig('pkg-config --cflags --libs libdrm xorg-server')
 
+if env['kms']:
+    env.Append(CPPDEFINES = ['HAVE_LIBKMS'])
+
 conf = env.Configure()
 
 if conf.CheckHeader('X11/extensions/dpmsconst.h'):