Actually, I had forgotten to disable the stack protector, and guess
what? Disabling it produces a working libstdc++, at least for that
simple use case; I have not tried to build cmake.
Therefore I suggest the following diff until someone with enough love
for the utter crap known as `arm' comes with a real compiler fix:
Index: Makefile
===================================================================
RCS file: /OpenBSD/src/gnu/lib/libstdc++-v3/Makefile,v
retrieving revision 1.8
diff -u -p -r1.8 Makefile
--- Makefile 14 May 2015 02:56:01 -0000 1.8
+++ Makefile 16 Feb 2016 20:04:20 -0000
@@ -17,6 +17,9 @@ CFLAGS+= -frandom-seed=RepeatabilityCons
CXXFLAGS+= -frandom-seed=RepeatabilityConsideredGood
CXXFLAGS+= -fno-implicit-templates -ffunction-sections -fdata-sections \
-Wno-deprecated
+.if ${MACHINE_ARCH} == "arm"
+CXXFLAGS+= -fno-stack-protector
+.endif
DPADD= ${LIBM}
LDADD= -lm
