conf.CheckCHeader lrdf.h check fails because of missing -I/usr/include/raptor2, use pkg-config instead

--- Sconstruct
+++ Sconstruct
@@ -268,7 +268,8 @@
 		env.Append( LIBPATH = 'C:\Program Files\GnuWin32\lib' )
 		env.Append( LIBS = [ "pthread" ] )
 	
-        if str(env['lrdf']) == "1": env.Append( LIBS = ["lrdf"] )
+        if str(env['lrdf']) == "1":
+		env.ParseConfig('pkg-config --cflags --libs lrdf')
 	if str(env['jack']) == "1": env.Append( LIBS = ["jack"])
 	if str(env['alsa']) == "1": env.Append( LIBS = ["asound"])
 	if str(env['libarchive']) == "1": env.Append( LIBS = ["archive"])
@@ -449,7 +450,7 @@
    Exit(1)
 
 #lrdf: categorizing of ladspa effects
-if str(env['lrdf']) == "1" and not conf.CheckCHeader('lrdf.h'):
+if str(env['lrdf']) == "1" and not conf.CheckPKG('lrdf >= 0.4.0'):
     print 'lrdf must be installed!'
     Exit(1)