[beast: 1/5] BUILD: configure.ac: detect LIBZ_LIBS and configure CXX to use C++11

[Tim Janik <timj src gnome org>]

commit 265b3e7902d24840e2d496be810c8afa305ca1b4
Author: Tim Janik <timj gnu org>
Date:   Wed Oct 12 16:58:28 2016 +0200

    BUILD: configure.ac: detect LIBZ_LIBS and configure CXX to use C++11
    
    Signed-off-by: Tim Janik <timj gnu org>

 configure.ac |   13 +++++++++++++
 1 files changed, 13 insertions(+), 0 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 81186a2..f63cff5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -141,12 +141,17 @@ ACX_PROG_LD_GNU_SYMBOLIC
 ACX_PROG_LD_GNU_DYNAMIC_LIST_CPP_NEW
 MC_EVAR_ADD(AM_LDFLAGS, $DYNAMIC_LIST_CPP_NEW_LDFLAGS)
 MC_EVAR_ADD(AM_LDFLAGS, -pthread)
+MC_EVAR_ADD(AM_LDFLAGS, -lpthread)
 MC_EVAR_ADD(AM_LDFLAGS, -lrt)
 MC_EVAR_ADD(AM_LDFLAGS, [-Wl,--no-undefined])
 if ${LD} --help 2>&1 | grep -q -- '-export-dynamic\b' ; then
   MC_EVAR_ADD(AM_LDFLAGS, [-Wl,-export-dynamic])
 fi
 
+# == C++ Dialect ==
+CXX="$CXX -std=gnu++11"
+test -z "$CXXCPP" || CXXCPP="$CXXCPP -std=gnu++11"
+
 # AM_LDFLAGS, optimize linker to use faster ELF symbol hashing if we have compiler and linker support
 AC_MSG_CHECKING([whether CC and LD support gnu.hash sections])
 if ${CC-cc} -dumpspecs | grep -q -- '--hash-style=\(both\|gnu\).*--as-needed' && \
@@ -266,6 +271,14 @@ AC_PROG_LN_S
 # require pkg-config
 MC_ASSERT_PROG(PKG_CONFIG, pkg-config, [pkg-config can be found at 
http://www.freedesktop.org/software/pkgconfig/])
 
+# == Libraries ==
+# libz
+AC_CHECK_LIB(z, gzsetparams, [AC_CHECK_HEADER(zlib.h, LIBZ_LIBS='-lz', LIBZ='')], LIBZ='')
+if test -z "$LIBZ_LIBS"; then
+    AC_MSG_ERROR([Compression library libz is missing, but required])
+fi
+AC_SUBST(LIBZ_LIBS)
+
 dnl #
 dnl # Define package requirements.
 dnl #