build/make/configure.sh: Silence arm target Xcode7 link warnings.

Always add IOS_VERSION_MIN to darwin arm cflags. The warning occured
because the default (9.0) does not match the value set by configure
(6.0).

BUG=https://code.google.com/p/webm/issues/detail?id=1075

Change-Id: Ia9085ceeca10e057f9eb781c14f07581bb6280a5

build/make/configure.sh

diff --git a/build/make/configure.sh b/build/make/configure.sh
index 4021ec4..abf2e42 100644
--- a/build/make/configure.sh
+++ b/build/make/configure.sh
@@ -742,6 +742,7 @@
   # platforms, so use the newest one available.
   case ${toolchain} in
     arm*-darwin*)
+      add_cflags "-miphoneos-version-min=${IOS_VERSION_MIN}"
       iphoneos_sdk_dir="$(show_darwin_sdk_path iphoneos)"
       if [ -d "${iphoneos_sdk_dir}" ]; then
         add_cflags  "-isysroot ${iphoneos_sdk_dir}"