fix code attempting to skip adding "-g" if "-g*" already is used.

in bsd.lib.mk there's a check for "MKDEBUG != no" that will add
-g to CFLAGS (maybe) and to CSHLIBFLAGS (always), given that it
isn't in CFLAGS already.. except the conditional is "||" instead
of "&&" and since the MKDEBUG/NODEBUG checks pass, the CFLAGS
check isn't even performed.

additionally, check CXXFLAGS as well as CFLAGS.

this fixes the attempt to use "-g1" in the llvmrt build, which
fails because the compile lines end up being "... -g1 .. -g ..",
(the "-g" comes from the CSHLIBFLAGS variable in that case.)

this reduces the size of llvm-enabled gallium debug by over 1GB.


Index: share/mk/bsd.lib.mk
===================================================================
RCS file: /cvsroot/src/share/mk/bsd.lib.mk,v
retrieving revision 1.389
diff -p -u -r1.389 bsd.lib.mk
--- share/mk/bsd.lib.mk	29 Mar 2022 22:48:04 -0000	1.389
+++ share/mk/bsd.lib.mk	5 Feb 2023 21:54:46 -0000
@@ -169,8 +169,10 @@ MKSHLIBOBJS= yes
 MKSHLIBOBJS= no
 .endif
 
-.if (${MKDEBUG:Uno} != "no" && !defined(NODEBUG)) || \
-    (defined(CFLAGS) && !empty(CFLAGS:M*-g*))
+# Avoid adding "-g" if we already have a "-g*" option.
+.if (${MKDEBUG:Uno} != "no" && !defined(NODEBUG)) && \
+    (!defined(CFLAGS) || empty(CFLAGS:M-g*)) && \
+    (!defined(CXXFLAGS) || empty(CXXFLAGS:M-g*))
 # We only add -g to the shared library objects
 # because we don't currently split .a archives.
 CSHLIBFLAGS+=	-g