pg_buildext: Copy CFLAGS from environment to COPT

pg_buildext: Copy CFLAGS from environment to COPT so Makefile.global picks it
up. Notably this will make extension builds use -f{debug,file}-prefix-map from
dpkg-buildflags.

debian/changelog

@@ -6,6 +6,9 @@ postgresql-common (193) UNRELEASED; urgency=medium
 
   [ Christoph Berg ]
   * pg_buildext: Stop passing srcdir to make invocations.
+  * pg_buildext: Copy CFLAGS from environment to COPT so Makefile.global
+    picks it up. Notably this will make extension builds use
+    -f{debug,file}-prefix-map from dpkg-buildflags.
 
  -- Christoph Berg <myon@debian.org>  Wed, 15 Aug 2018 17:59:38 +0200
 

pg_buildext

@@ -50,6 +50,9 @@ prepare_env() {
     vtarget=`echo $target | sed -e "s:%v:$version:g"`
     pgc="/usr/lib/postgresql/$version/bin/pg_config"
     [ -e "$pgc" ] || die "$pgc does not exist"
+    if [ "$CFLAGS" ]; then
+        export COPT="$CFLAGS"
+    fi
 }
 
 configure() {