Overwrite MSGMERGE_FLAGS, not MSGMERGE.

maint/mctest

@@ -10,7 +10,7 @@ trap 'echo >&2 "ERROR: Test not completed, exit with code $?"; exit 1' exit
 distcheck() {
     id="$1"
     shift
-    make distcheck MSGMERGE="msgmerge -q" "$@" >test-$id.out 2>test-$id.err
+    make distcheck $MAKEFLAGS "$@" >test-$id.out 2>test-$id.err
 }
 
 # Specify which warnings we want to see.
@@ -22,7 +22,7 @@ export CFLAGS="-O2 -Wall -Wno-unused-parameter -Wno-sign-compare \
 -Wcast-align -Wpointer-arith -Wredundant-decls -Wundef -Wfloat-equal"
 
 # Suppress progress indicator
-export MSGMERGE="msgmerge --quiet"
+MAKEFLAGS='MSGMERGE_FLAGS=--no-location --quiet'
 
 echo "Checking the documentation"
 maint/doctest