https://github.com/MapServer/MapServer/issues/6249

From e56a020789c024f985c61e49d66f3eb92d350232 Mon Sep 17 00:00:00 2001
From: Even Rouault <even.rouault@spatialys.com>
Date: Mon, 8 Mar 2021 15:19:50 +0100
Subject: [PATCH] FindProj.cmake: allow finding PROJ 8 that has no longer
 proj_api.h (fixes #6249)

--- a/cmake/FindProj.cmake
+++ b/cmake/FindProj.cmake
@@ -6,7 +6,7 @@
 #    PROJ_LIBRARY
 
 
-FIND_PATH(PROJ_INCLUDE_DIR proj_api.h)
+FIND_PATH(PROJ_INCLUDE_DIR NAMES proj.h proj_api.h)
 
 FIND_LIBRARY(PROJ_LIBRARY NAMES proj proj_i)