gcc can't generate dependencies for a file that doesn't exist, so first create SDL_revision.h

--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%404049

autogen.sh

@@ -3,6 +3,9 @@
 echo "Generating build information using autoconf"
 echo "This may take a while ..."
 
+# Generate SDL_revision.h
+sh build-scripts/updaterev.sh
+
 # Regenerate configuration files
 cat acinclude/* >aclocal.m4
 found=false