Update build-infer.sh for Mojave

Summary:
Building infer from source fails on OSX Mojave, see https://github.com/facebook/infer/issues/1026

This commit adds the fix from https://github.com/facebook/infer/issues/1026 to the build script

Reviewed By: ngorogiannis

Differential Revision: D16031929

fbshipit-source-id: 3450877f4

build-infer.sh

@@ -142,6 +142,17 @@ echo >&2
 echo "installing infer dependencies; this can take up to 30 minutes... " >&2
 opam_retry install_opam_deps
 
+#fix for Mojave
+if [ "$OSTYPE" == "darwin18" ]; then
+    if [ "$(command -v xcode-select)" == "" ]; then
+        xcode-select --install
+    fi
+    SDKROOT=${SDKROOT:-/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk}
+    if [ -d "$SDKROOT" ]; then
+        export SDKROOT
+    fi
+fi
+
 if [ "$ONLY_SETUP_OPAM" == "yes" ]; then
   exit 0
 fi