8273072: Avoid using += in configure

Reviewed-by: dholmes, jiefu

make/autoconf/flags-cflags.m4

@@ -137,7 +137,7 @@ AC_DEFUN([FLAGS_SETUP_WARNINGS],
       DISABLED_WARNINGS="4800"
       if test "x$TOOLCHAIN_VERSION" = x2017; then
         # VS2017 incorrectly triggers this warning for constexpr
-        DISABLED_WARNINGS+=" 4307"
+        DISABLED_WARNINGS="$DISABLED_WARNINGS 4307"
       fi
       ;;
 

make/autoconf/flags-other.m4

@@ -89,11 +89,12 @@ AC_DEFUN([FLAGS_SETUP_ASFLAGS],
 
     # Fix linker warning.
     # Code taken from make/autoconf/flags-cflags.m4 and adapted.
-    JVM_BASIC_ASFLAGS+=" -DMAC_OS_X_VERSION_MIN_REQUIRED=$MACOSX_VERSION_MIN_NODOTS \
+    JVM_BASIC_ASFLAGS="$JVM_BASIC_ASFLAGS \
+        -DMAC_OS_X_VERSION_MIN_REQUIRED=$MACOSX_VERSION_MIN_NODOTS \
         -mmacosx-version-min=$MACOSX_VERSION_MIN"
 
     if test -n "$MACOSX_VERSION_MAX"; then
-        JVM_BASIC_ASFLAGS+=" $OS_CFLAGS \
+        JVM_BASIC_ASFLAGS="$JVM_BASIC_ASFLAGS $OS_CFLAGS \
             -DMAC_OS_X_VERSION_MAX_ALLOWED=$MACOSX_VERSION_MAX_NODOTS"
     fi
   fi

make/autoconf/jdk-version.m4

@@ -1,5 +1,5 @@
 #
-# Copyright (c) 2015, 2019, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2015, 2021, Oracle and/or its affiliates. All rights reserved.
 # DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 #
 # This code is free software; you can redistribute it and/or modify it
@@ -525,7 +525,7 @@ AC_DEFUN_ONCE([JDKVER_SETUP_JDK_VERSION_NUMBERS],
     MACOSX_BUNDLE_BUILD_VERSION="$VERSION_BUILD"
     # If VERSION_OPT consists of only numbers and periods, add it.
     if [ [[ $VERSION_OPT =~ ^[0-9\.]+$ ]] ]; then
-      MACOSX_BUNDLE_BUILD_VERSION+=".$VERSION_OPT"
+      MACOSX_BUNDLE_BUILD_VERSION="$MACOSX_BUNDLE_BUILD_VERSION.$VERSION_OPT"
     fi
   fi
   AC_SUBST(MACOSX_BUNDLE_BUILD_VERSION)

make/devkit/createMacosxDevkit.sh

@@ -1,6 +1,6 @@
 #!/bin/bash
 #
-# Copyright (c) 2015, 2020, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2015, 2021, Oracle and/or its affiliates. All rights reserved.
 # DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 #
 # This code is free software; you can redistribute it and/or modify it
@@ -102,7 +102,7 @@ EXCLUDE_DIRS=" \
 "
 
 for ex in $EXCLUDE_DIRS; do
-    EXCLUDE_ARGS+="--exclude=$ex "
+    EXCLUDE_ARGS="$EXCLUDE_ARGS --exclude=$ex"
 done
 
 echo "Copying Xcode.app..."