[build] save the value of PLUGIN_SETUP_SCRIPT from ./configure

Summary:
This avoids the need for setting `PLUGIN_SETUP_SCRIPT` for every `make`
command, or `export`ing it.

Reviewed By: ngorogiannis

Differential Revision: D62244878

fbshipit-source-id: ea514cf841b3a1d27d0181d05751200338592fdf

Makefile

@@ -481,8 +481,6 @@ byte_infer: byte
 opt:
 	$(QUIET)$(MAKE) BUILD_MODE=opt infer
 
-PLUGIN_SETUP_SCRIPT ?= setup.sh
-
 .PHONY: clang_setup
 clang_setup:
 #	if clang is already built then let the user know they might not need to rebuild clang

Makefile.autoconf.in

@@ -85,6 +85,7 @@ OTOOL := @OTOOL@
 PATCHELF := @PATCHELF@
 PATH := @PATH@
 PLATFORM_ENV := @PLATFORM_ENV@
+PLUGIN_SETUP_SCRIPT := @PLUGIN_SETUP_SCRIPT@
 prefix := @prefix@
 PYTHON := @PYTHON@
 PYTHONHOME := @PYTHONHOME@

configure.ac

@@ -100,6 +100,11 @@ AC_SUBST([REALPATH])
 
 AC_ARG_VAR([PLATFORM_ENV], [Build and link binaries against this platform rather than system default (Linux only)])
 
+AC_MSG_CHECKING([for the name of the plugin setup script])
+AC_ARG_VAR([PLUGIN_SETUP_SCRIPT], [name of the setup script for building clang (default: setup.sh)])
+AS_IF([test x"$PLUGIN_SETUP_SCRIPT" = x], [PLUGIN_SETUP_SCRIPT=setup.sh])
+AC_MSG_RESULT([$PLUGIN_SETUP_SCRIPT])
+
 AC_ARG_ENABLE(c-analyzers,
   AS_HELP_STRING([--disable-c-analyzers],
     [do not build the C/C++/ObjC analyzers (default is to build them)]),