how do I fix this header conflict?

[Benjamin Reed]

In acinclude.m4.in there is a line that adds the flag "-pedantic-errors"
to CXXFLAGS.  On Mac OS X, this causes issues when configure gets very
long and the c preprocessor gets out-of-bounds errors:

---(snip!)---
configure:32891: checking for initgroups
configure:32942: g++ -c -Wnon-virtual-dtor -Wno-long-long -Wundef -Wall
  -pedantic -W -Wpointer-arith -Wwrite-strings -O2 -fno-exceptions
  -fno-check-new -fno-common -pedantic-errors  -DQT_THREAD_SUPPORT
  -I/usr/X11R6/include -I/opt/local/include -I/opt/local/include/qt3
  -no-cpp-precomp -fno-common conftest.cc >&5
conftest.cc:1:7: line number out of range
configure:32945: $? = 1
---(snip!)---

When this happens, configure assumes I don't have the function and
enables the version in libkdefakes instead.  This causes conflicts when
the kdefakes version gets in the way of the version in the system
libraries:

---(snip!)---
In file included from dcopserver.cpp:39:
/usr/include/unistd.h:215: error: declaration of C function `int
   initgroups(const char*, int)' conflicts with
../config.h:810: error: previous declaration `int initgroups(const
   char*, unsigned int)' here
make[4]: *** [dcopserver.lo] Error 1
---(snip!)---

The thing that fixes it for me is to change "-pedantic-errors" to
"-pedantic", but last time I asked about this I got a lot of backlash.
Since that is not a proper solution, what is?