Determine CXXFLAGS after the C++ compiler was detected. Also honor

--enable-debug and environment variable override.

src/makefiles/Makefile.qnx4

@@ -14,3 +14,6 @@ CFLAGS_SL =
 
 %$(DLSUFFIX): %.o
 	@echo 'cannot make shared object $@ from $<'
+
+# Hack alert!  Fix your compiler installation...
+override CXXFLAGS +=-I/usr/local/lib/gcc-lib/i386-pc-qnx4/egcs-2.91.60/include/g++

src/template/aix

@@ -1,6 +1,5 @@
 if test "$GCC" = yes ; then
   CFLAGS=-pipe
-  CXXFLAGS=-pipe
 else # not GCC
   case $host_os in
     aix3.2.5)

src/template/osf

@@ -5,5 +5,4 @@ else
   CC="$CC -std"
   CFLAGS='-O4 -Olimit 2000'
   CCC=cxx
-  CXXFLAGS='-O4 -Olimit 2000'
 fi

src/template/qnx4

@@ -1,3 +1,2 @@
 CFLAGS=
 LIBS=-lunix
-CXXFLAGS=-I/usr/local/lib/gcc-lib/i386-pc-qnx4/egcs-2.91.60/include/g++