[build] fix ./build-infer.sh

Summary: Need to set INFER_OPAM_COMPILER to a default value.

Reviewed By: jberdine

Differential Revision: D18615861

fbshipit-source-id: 78b29fb75

build-infer.sh

@@ -18,7 +18,9 @@ PLATFORM="$(uname)"
 SANDCASTLE=${SANDCASTLE:-}
 NCPU="$(getconf _NPROCESSORS_ONLN 2>/dev/null || echo 1)"
 INFER_OPAM_DEFAULT_SWITCH="ocaml-variants.4.07.1+flambda"
+INFER_OPAM_DEFAULT_COMPILER="$INFER_OPAM_DEFAULT_SWITCH"
 INFER_OPAM_SWITCH=${INFER_OPAM_SWITCH:-$INFER_OPAM_DEFAULT_SWITCH}
+INFER_OPAM_COMPILER=${INFER_OPAM_COMPILER:-$INFER_OPAM_DEFAULT_COMPILER}
 
 function usage() {
   echo "Usage: $0 [-y] [targets]"