build: change include_directories order

Listing 'include/dav1d' before 'include' prefers the generated version.h
in include/dav1d/ over the previous one in include/. This allows the use
of '#include "version.h"' in dav1d.h. See !592.

meson.build

@@ -45,7 +45,7 @@ cdata = configuration_data()
 cdata_asm = configuration_data()
 
 # Include directories
-dav1d_inc_dirs = include_directories(['.', 'include', 'include/dav1d'])
+dav1d_inc_dirs = include_directories(['.', 'include/dav1d', 'include'])