pcc and build system

[Gregory McGarry <g.mcgarry%ieee.org@localhost>]

How should alternative compilers be integrated into the build  
system?  Can patches like the one below be sprinkled round the the  
build tree and bsd.own.mk changed later to define HAVE_PCC?  I  
currently define HAVE_PCC in my environment.

Index: Makefile
===================================================================
RCS file: /cvsroot/src/lib/libpcap/Makefile,v
retrieving revision 1.30
diff -u -r1.30 Makefile
--- Makefile    28 May 2007 12:06:20 -0000      1.30
+++ Makefile    7 Jul 2008 13:30:19 -0000
@@ -19,7 +19,12 @@
 YHEADER=       1

 CPPFLAGS+=     -DHAVE_CONFIG_H
+
+.if defined(HAVE_PCC)
+CPPFLAGS+=     -D_U_=""
+.elif defined(HAVE_GCC)
 CPPFLAGS+=     -D_U_="__attribute__((unused))"
+.endif

 .if (${USE_INET6} != "no")
 CPPFLAGS+=     -DINET6