Add LIBTOOL_LDFLAGS configure variable

configure.ac

@@ -140,6 +140,9 @@ AC_ARG_WITH([cython],
 dnl Define variables
 AC_ARG_VAR([CYTHON], [the Cython executable])
 
+AC_ARG_VAR([LIBTOOL_LDFLAGS],
+           [libtool specific flags (e.g., -static-libtool-libs)])
+
 dnl Checks for programs
 AC_PROG_CC
 AC_PROG_CXX
@@ -886,6 +889,8 @@ AC_MSG_NOTICE([summary of build options:
     Library:
       Shared:         ${enable_shared}
       Static:         ${enable_static}
+    Libtool:
+      LIBTOOL_LDFLAGS: ${LIBTOOL_LDFLAGS}
     Python:
       Python:         ${PYTHON}
       PYTHON_VERSION: ${PYTHON_VERSION}

examples/Makefile.am

@@ -35,6 +35,7 @@ AM_CPPFLAGS = \
 	@LIBEVENT_OPENSSL_CFLAGS@ \
 	@OPENSSL_CFLAGS@ \
 	@DEFS@
+AM_LDFLAGS = @LIBTOOL_LDFLAGS@
 LDADD = $(top_builddir)/lib/libnghttp2.la \
 	$(top_builddir)/third-party/liburl-parser.la \
 	@LIBEVENT_OPENSSL_LIBS@ \

lib/Makefile.am

@@ -27,6 +27,7 @@ EXTRA_DIST = Makefile.msvc CMakeLists.txt version.rc.in
 AM_CFLAGS = $(WARNCFLAGS) $(EXTRACFLAG)
 AM_CPPFLAGS = -I$(srcdir)/includes -I$(builddir)/includes -DBUILDING_NGHTTP2 \
 	@DEFS@
+AM_LDFLAGS = @LIBTOOL_LDFLAGS@
 
 pkgconfigdir = $(libdir)/pkgconfig
 pkgconfig_DATA = libnghttp2.pc
@@ -70,5 +71,5 @@ HFILES = nghttp2_pq.h nghttp2_int.h nghttp2_map.h nghttp2_queue.h \
 	nghttp2_ksl.h
 
 libnghttp2_la_SOURCES = $(HFILES) $(OBJECTS)
-libnghttp2_la_LDFLAGS = -no-undefined \
+libnghttp2_la_LDFLAGS = $(AM_LDFLAGS) -no-undefined \
 	-version-info $(LT_CURRENT):$(LT_REVISION):$(LT_AGE)

src/Makefile.am

@@ -48,6 +48,7 @@ AM_CPPFLAGS = \
 	@JANSSON_CFLAGS@ \
 	@ZLIB_CFLAGS@ \
 	@DEFS@
+AM_LDFLAGS = @LIBTOOL_LDFLAGS@
 
 LDADD = $(top_builddir)/lib/libnghttp2.la \
 	$(top_builddir)/third-party/liburl-parser.la \
@@ -262,7 +263,7 @@ libnghttp2_asio_la_SOURCES = \
 	asio_client_tls_context.cc asio_client_tls_context.h
 
 libnghttp2_asio_la_CPPFLAGS = ${AM_CPPFLAGS} ${BOOST_CPPFLAGS}
-libnghttp2_asio_la_LDFLAGS = -no-undefined -version-info 1:0:0
+libnghttp2_asio_la_LDFLAGS = $(AM_LDFLAGS) -no-undefined -version-info 1:0:0
 libnghttp2_asio_la_LIBADD = \
 	$(top_builddir)/lib/libnghttp2.la \
 	$(top_builddir)/third-party/liburl-parser.la \