Add a comment about why $(CPP) is defined the way it is in config.mk.in

diff --git a/mk/config.mk.in b/mk/config.mk.in
index a400af9..b436235 100644 (file)
--- a/mk/config.mk.in
+++ b/mk/config.mk.in
@@ -569,6 +569,8 @@ BASH                    = /usr/local/bin/bash
 
 CONTEXT_DIFF           = @ContextDiffCmd@
 CP                     = cp
+# It's not easy to separate the CPP program from its flags, as
+# AC_PROG_CPP defines CPP as "/usr/bin/gcc -E"
 CPP                    = @CPP@ @CPPFLAGS@
 CTAGS                  = $(ETAGS)
 #