[cleanup] remove DIFF_CAN_FORMAT

Summary: As per title, this is no longer used.

Reviewed By: jvillard

Differential Revision:
D59812193

Privacy Context Container: L1208441

fbshipit-source-id: 7b4369ac47f353ceaadf659590277e23acd430ea

Makefile

@@ -935,10 +935,6 @@ devsetup:
 	  echo '$(TERM_INFO)*** Installing GNU sed$(TERM_RESET)' >&2; \
 	  brew install gnu-sed; \
 	fi
-	$(QUIET)if [ "$(PLATFORM)" = "Darwin" ] && [ x"$(DIFF_CAN_FORMAT)" = x"no" ] ; then \
-	  echo '$(TERM_INFO)*** Installing diffutils$(TERM_RESET)' >&2; \
-	  brew install diffutils; \
-	fi
 	$(QUIET)if [ "$(PLATFORM)" = "Darwin" ] && ! $$(parallel -h | grep -q GNU); then \
 	  echo '$(TERM_INFO)*** Installing GNU parallel$(TERM_RESET)' >&2; \
 	  brew install parallel; \

Makefile.autoconf.in

@@ -29,7 +29,6 @@ CXX := @CXX@
 CXXFLAGS := @CXXFLAGS@
 # this is useless but autoconf is picky...
 datarootdir = @datarootdir@
-DIFF_CAN_FORMAT := @DIFF_CAN_FORMAT@
 EMACS := @EMACS@
 ENABLE_OCAMLOPT_CUSTOM_CC := @ENABLE_OCAMLOPT_CUSTOM_CC@
 ENABLE_OCAML_BINANNOT := @ENABLE_OCAML_BINANNOT@

configure.ac

@@ -474,16 +474,6 @@ AS_IF([test "$SED" != "xno"], [
 ])
 AC_SUBST([GNU_SED])
 
-AC_ASSERT_PROG([diff], [$DIFF])
-AC_MSG_CHECKING([if diff supports --LTYPE-line-format=LFMT options])
-# there are several such options but just test one of them and hope for the best
-AS_IF([diff --unchanged-line-format=A /dev/null /dev/null 2>/dev/null], [
-  DIFF_CAN_FORMAT=yes
-], [
-  DIFF_CAN_FORMAT=no
-])
-AC_MSG_RESULT([$DIFF_CAN_FORMAT])
-AC_SUBST([DIFF_CAN_FORMAT])
 
 AC_CHECK_TOOL([BREW], [brew], [no])
 AC_CHECK_TOOL([INSTALL_NAME_TOOL], [install_name_tool], [no])