libbacktrace: Suppress the default action-if-found for AC_CHECK_LIBS.

Zlib is not a dependency of libbacktrace, and so it shouldn't be added
to LIBS.

libbacktrace/

	* configure.ac: Move define of HAVE_ZLIB into check for -lz.
	* Makefile.in: Regenerate.
	* config.h.in: Likewise.
	* configure: Likewise.

From-SVN: r263320

libbacktrace/ChangeLog

+2018-08-05 Iain Buclaw  <ibuclaw@gdcproject.org>
+
+	* configure.ac: Move define of HAVE_ZLIB into check for -lz.
+	* Makefile.in: Regenerate.
+	* config.h.in: Likewise.
+	* configure: Likewise.
+
 2018-08-01  Tony Reix  <tony.reix@atos.net>
 
 	* xcoff.c (struct xcoff_line, struct xcoff_line_vector): Remove.

libbacktrace/Makefile.in

@@ -16,7 +16,7 @@
 @SET_MAKE@
 
 # Makefile.am -- Backtrace Makefile.
-# Copyright (C) 2012-2017 Free Software Foundation, Inc.
+# Copyright (C) 2012-2018 Free Software Foundation, Inc.
 
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are

libbacktrace/config.h.in

@@ -34,9 +34,6 @@
 /* Define to 1 if you have the <inttypes.h> header file. */
 #undef HAVE_INTTYPES_H
 
-/* Define to 1 if you have the `z' library (-lz). */
-#undef HAVE_LIBZ
-
 /* Define to 1 if you have the <link.h> header file. */
 #undef HAVE_LINK_H
 

libbacktrace/configure

@@ -12973,19 +12973,11 @@ fi
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_z_compress" >&5
 $as_echo "$ac_cv_lib_z_compress" >&6; }
 if test "x$ac_cv_lib_z_compress" = x""yes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_LIBZ 1
-_ACEOF
-
-  LIBS="-lz $LIBS"
-
-fi
-
-if test $ac_cv_lib_z_compress = "yes"; then
 
 $as_echo "#define HAVE_ZLIB 1" >>confdefs.h
 
 fi
+
  if test "$ac_cv_lib_z_compress" = yes; then
   HAVE_ZLIB_TRUE=
   HAVE_ZLIB_FALSE='#'

libbacktrace/configure.ac

@@ -426,10 +426,8 @@ AC_SUBST(PTHREAD_CFLAGS)
 
 AM_CONDITIONAL(HAVE_PTHREAD, test "$libgo_cv_lib_pthread" = yes)
 
-AC_CHECK_LIB([z], [compress], [])
-if test $ac_cv_lib_z_compress = "yes"; then
-  AC_DEFINE(HAVE_ZLIB, 1, [Define if -lz is available.])
-fi
+AC_CHECK_LIB([z], [compress],
+    [AC_DEFINE(HAVE_ZLIB, 1, [Define if -lz is available.])])
 AM_CONDITIONAL(HAVE_ZLIB, test "$ac_cv_lib_z_compress" = yes)
 
 dnl Test whether the linker supports the --compress_debug_sections option.