With gold linker build fails with:
g-ir-scanner: link: /bin/sh ../libtool --mode=link --tag=CC x86_64-pc-linux-gnu-gcc -o /ubuntu/var/tmp/portage/net-misc/networkmanager-1.2.2/work/NetworkManager-1.2.2-abi_x86_64.amd64/libnm/tmp-introspectPb5Gkb/NM-1.0 -export-dynamic -march=native -O2 -pipe -Wl,-O1 -Wno-error -Wl,--as-needed tmp-introspectPb5Gkb/ubuntu/var/tmp/portage/net-misc/networkmanager-1.2.2/work/NetworkManager-1.2.2-abi_x86_64.amd64/libnm/tmp-introspectPb5Gkb/NM-1.0.o -L. libnm.la -Wl,--export-dynamic -lgmodule-2.0 -pthread -lgio-2.0 -lgudev-1.0 -lgobject-2.0 -lglib-2.0
libtool: link: x86_64-pc-linux-gnu-gcc -o /ubuntu/var/tmp/portage/net-misc/networkmanager-1.2.2/work/NetworkManager-1.2.2-abi_x86_64.amd64/libnm/tmp-introspectPb5Gkb/.libs/NM-1.0 -march=native -O2 -pipe -Wl,-O1 -Wno-error tmp-introspectPb5Gkb/ubuntu/var/tmp/portage/net-misc/networkmanager-1.2.2/work/NetworkManager-1.2.2-abi_x86_64.amd64/libnm/tmp-introspectPb5Gkb/NM-1.0.o -Wl,--export-dynamic -pthread -Wl,--export-dynamic  -Wl,--as-needed -L. ./.libs/libnm.so -lssl3 -lsmime3 -lnss3 -lnssutil3 -lplds4 -lplc4 -lnspr4 -luuid -lgmodule-2.0 -lgio-2.0 -lgudev-1.0 -lgobject-2.0 -lglib-2.0 -pthread
./.libs/libnm.so: error: undefined reference to 'dlopen'
./.libs/libnm.so: error: undefined reference to 'dlsym'
./.libs/libnm.so: error: undefined reference to 'dlerror'
./.libs/libnm.so: error: undefined reference to 'dlclose'
collect2: error: ld returned 1 exit status
linking of temporary binary failed: Command '['/bin/sh', '../libtool', '--mode=link', '--tag=CC', 'x86_64-pc-linux-gnu-gcc', '-o', '/ubuntu/var/tmp/portage/net-misc/networkmanager-1.2.2/work/NetworkManager-1.2.2-abi_x86_64.amd64/libnm/tmp-introspectPb5Gkb/NM-1.0', '-export-dynamic', '-march=native', '-O2', '-pipe', '-Wl,-O1', '-Wno-error', '-Wl,--as-needed', 'tmp-introspectPb5Gkb/ubuntu/var/tmp/portage/net-misc/networkmanager-1.2.2/work/NetworkManager-1.2.2-abi_x86_64.amd64/libnm/tmp-introspectPb5Gkb/NM-1.0.o', '-L.', 'libnm.la', '-Wl,--export-dynamic', '-lgmodule-2.0', '-pthread', '-lgio-2.0', '-lgudev-1.0', '-lgobject-2.0', '-lglib-2.0']' returned non-zero exit status 1
/usr/share/gobject-introspection-1.0/Makefile.introspection:155: recipe for target 'NM-1.0.gir' failed
make[4]: *** [NM-1.0.gir] Error 1
make[4]: Leaving directory '/ubuntu/var/tmp/portage/net-misc/networkmanager-1.2.2/work/NetworkManager-1.2.2-abi_x86_64.amd64/libnm'
Makefile:1083: recipe for target 'all-recursive' failed
make[3]: *** [all-recursive] Error 1
make[3]: Leaving directory '/ubuntu/var/tmp/portage/net-misc/networkmanager-1.2.2/work/NetworkManager-1.2.2-abi_x86_64.amd64/libnm'
Makefile:843: recipe for target 'all' failed
make[2]: *** [all] Error 2
make[2]: Leaving directory '/ubuntu/var/tmp/portage/net-misc/networkmanager-1.2.2/work/NetworkManager-1.2.2-abi_x86_64.amd64/libnm'
Makefile:645: recipe for target 'all-recursive' failed
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory '/ubuntu/var/tmp/portage/net-misc/networkmanager-1.2.2/work/NetworkManager-1.2.2-abi_x86_64.amd64'
Makefile:554: recipe for target 'all' failed
make: *** [all] Error 2

This patch from downstream report fixes the problem:
https://bugs.gentoo.org/show_bug.cgi?id=588474
diff -urN NetworkManager-1.2.2/libnm/Makefile.in NetworkManager-1.2.2-patched/libnm/Makefile.in
--- NetworkManager-1.2.2/libnm/Makefile.in	2016-05-11 20:54:18.000000000 +0930
+++ NetworkManager-1.2.2-patched/libnm/Makefile.in	2016-07-11 07:50:54.372966460 +0930
@@ -913,7 +913,7 @@
 	}
 
 libnm.la: $(libnm_la_OBJECTS) $(libnm_la_DEPENDENCIES) $(EXTRA_libnm_la_DEPENDENCIES) 
-	$(AM_V_CCLD)$(libnm_la_LINK) -rpath $(libdir) $(libnm_la_OBJECTS) $(libnm_la_LIBADD) $(LIBS)
+	$(AM_V_CCLD)$(libnm_la_LINK) -rpath $(libdir) $(libnm_la_OBJECTS) $(libnm_la_LIBADD) $(LIBS) $(LIBDL)
 
 mostlyclean-compile:
 	-rm -f *.$(OBJEXT)