Pass -isysroot to both CFLAGS and LDFLAGS when building ninja (swiftlang#33414)

* Pass -isysroot to both CFLAGS and LDFLAGS when building ninja

* Update test expectations too

Author: kubamracek

utils/swift_build_support/swift_build_support/products/ninja.py

@@ -63,8 +63,8 @@ def build(self):
                     "-isysroot {sysroot} -mmacosx-version-min={osx_version}"
                 ).format(sysroot=sysroot, osx_version=osx_version_min),
                 "LDFLAGS": (
-                    "-mmacosx-version-min={osx_version}"
-                ).format(osx_version=osx_version_min),
+                    "-isysroot {sysroot} -mmacosx-version-min={osx_version}"
+                ).format(sysroot=sysroot, osx_version=osx_version_min),
             }
         elif self.toolchain.cxx:
             env = {

utils/swift_build_support/tests/products/test_ninja.py

@@ -101,7 +101,7 @@ def test_build(self):
                 "env "
                 "'CFLAGS=-isysroot {sysroot} -mmacosx-version-min=10.9' "
                 "CXX={cxx} "
-                "LDFLAGS=-mmacosx-version-min=10.9 "
+                "'LDFLAGS=-isysroot {sysroot} -mmacosx-version-min=10.9' "
             ).format(
                 cxx=self.toolchain.cxx,
                 sysroot=xcrun.sdk_path('macosx')