Fix Makefile.autoconf.in

Reviewed By: jvillard

Differential Revision: D4946043

fbshipit-source-id: 662de3c

Makefile.autoconf.in

@@ -71,5 +71,7 @@ endif
 
 # Export parts of the config relevant to running other programs
 # be merciful and allow PATH to be updated between ./configure and make
-export PATH := $(shell printf "%s" "$$PATH"):$(PATH)
+# except for OCaml-related executables
+# TODO(17630614) get rid of this hack
+export PATH := $(dir $(OCAMLC)):$(shell printf "%s" "$$PATH"):$(PATH)
 export CAML_LD_LIBRARY_PATH := $(CAML_LD_LIBRARY_PATH)