Re-add proj include to grass provider

Author: nyalldawson

src/providers/grass/CMakeLists.txt

@@ -17,6 +17,7 @@ INCLUDE_DIRECTORIES(
 )
 INCLUDE_DIRECTORIES (SYSTEM
   ${GDAL_INCLUDE_DIR}
+  ${PROJ_INCLUDE_DIR}
   ${POSTGRES_INCLUDE_DIR}
 )