newlib: xtensa fix for CFLAGS_FOR_TARGET

We need to have config files do a += otherwise if we try and set
CFLAGS_FOR_TARGET as part of configuring newlib the setting will not
propogate.  This fix is just for the xtensa newlib version as the
upstream version already has this change in place for config/mt-ospace

Signed-off-by: Kumar Gala <[email protected]>

Author: galak

patches/newlib/git-b06f1b57/0001-fix-mt-cflags.patch

@@ -0,0 +1,12 @@
+---
+ config/mt-ospacev |    4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+--- a/config/mt-ospace	2019-02-14 10:27:54.764350561 -0600
++++ b/config/mt-ospace	2019-02-14 10:28:11.934912980 -0600
+@@ -1,3 +1,3 @@
+ # Build libraries optimizing for space, not speed.
+- CFLAGS_FOR_TARGET = -g -Os
+- CXXFLAGS_FOR_TARGET = -g -Os
++ CFLAGS_FOR_TARGET += -g -Os
++ CXXFLAGS_FOR_TARGET += -g -Os