Use $BDW_GC_LIBS instead of a custom variable.

configure.ac

@@ -268,11 +268,9 @@ AC_ARG_ENABLE(gc, AC_HELP_STRING([--enable-gc],
   gc=$enableval, gc=)
 if test -n "$gc"; then
   PKG_CHECK_MODULES([BDW_GC], [bdw-gc])
-  boehmgc_lib="$BDW_GC_LIBS"
   CXXFLAGS="$BDW_GC_CFLAGS $CXXFLAGS"
   AC_DEFINE(HAVE_BOEHMGC, 1, [Whether to use the Boehm garbage collector.])
 fi
-AC_SUBST(boehmgc_lib)
 
 
 AC_ARG_ENABLE(init-state, AC_HELP_STRING([--disable-init-state],

src/libexpr/Makefile.am

@@ -11,7 +11,7 @@ pkginclude_HEADERS = \
  names.hh symbol-table.hh
 
 libexpr_la_LIBADD = ../libutil/libutil.la ../libstore/libstore.la \
- ../boost/format/libformat.la @boehmgc_lib@
+ ../boost/format/libformat.la @BDW_GC_LIBS@
 
 BUILT_SOURCES = \
  parser-tab.hh lexer-tab.hh parser-tab.cc lexer-tab.cc

src/libmain/Makefile.am

@@ -2,7 +2,7 @@ pkglib_LTLIBRARIES = libmain.la
 
 libmain_la_SOURCES = shared.cc
 
-libmain_la_LIBADD = ../libstore/libstore.la @boehmgc_lib@
+libmain_la_LIBADD = ../libstore/libstore.la @BDW_GC_LIBS@
 
 pkginclude_HEADERS = shared.hh