libc/newlib: add option to optimise for size

Add an option to build with -Os instead of the default -O.

Reviewed-by: Michael Hope
Signed-off-by: Zhenqiang Chen <zhenqiang.chen@linaro.org>

config/libc/newlib.in.2

@@ -35,6 +35,15 @@ config LIBC_NEWLIB_DISABLE_SUPPLIED_SYSCALLS
 	  _write... If you plan to port newlib to a new
 	  platform/board, say Yes.
 
+config LIBC_NEWLIB_ENABLE_TARGET_OPTSPACE
+    bool
+    prompt "Optimize newlib for size"
+    default y
+    help
+      Pass --enable-target-optspace to newlib configure.
+      
+      This will compile newlib with -Os.
+
 config LIBC_NEWLIB_EXTRA_CONFIG_ARRAY
     string
     prompt "Extra config for newlib"

scripts/build/libc/newlib.sh

@@ -85,6 +85,8 @@ do_libc_start_files() {
         newlib_opts+=( "--enable-newlib-supplied-syscalls" )
     fi
 
+    [ "${CT_LIBC_NEWLIB_ENABLE_TARGET_OPTSPACE}" = "y" ] && newlib_opts+=("--enable-target-optspace")
+
     # Note: newlib handles the build/host/target a little bit differently
     # than one would expect:
     #   build  : not used