[newlib-cygwin] config/mt-d30v: Append flags

[Jeff Johnston]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=28489b0702556eb183029750b0292fa3d59d31c0

commit 28489b0702556eb183029750b0292fa3d59d31c0
Author: Chris Packham <judge.packham@gmail.com>
Date:   Sun May 28 15:05:45 2023 +1200

    config/mt-d30v: Append flags
    
    Append to CFLAGS_FOR_TARGET/CXXFLAGS_FOR_TARGET rather than replacing
    them.
    
    Signed-off-by: Chris Packham <judge.packham@gmail.com>

Diff:
---
 config/mt-d30v | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/config/mt-d30v b/config/mt-d30v
index d34b774b3..f5081aef5 100644
--- a/config/mt-d30v
+++ b/config/mt-d30v
@@ -1,4 +1,4 @@
 # Build libraries optimizing for space, not speed.
 # Turn off warnings about symbols named the same as registers
- CFLAGS_FOR_TARGET = -g -Os -Wa,-C
- CXXFLAGS_FOR_TARGET = -g -Os -Wa,-C
+ CFLAGS_FOR_TARGET += -g -Os -Wa,-C
+ CXXFLAGS_FOR_TARGET += -g -Os -Wa,-C