Silence the warnings about strlen() operating on char *

This fixes the following warnings:
---
cweave.w:4462:8: warning: passing 'eight_bits *' (aka 'unsigned char *') to parameter of type 'char *' converts between pointers to integer types with different sign
      [-Wpointer-sign]
strcpy(collate+213,"\360\361\362\363\364\365\366\367\370\371\372\373\374\375\376\377");
---

Makefile

@@ -50,7 +50,7 @@ TCHANGES=
 WCHANGES=
 
 # We keep debugging info around, for fun, but most users don't need it
-CFLAGS = -g
+CFLAGS = -g -Wno-pointer-sign
 #CFLAGS = -O
 LINKFLAGS = -g
 #LINKFLAGS = -s # for smaller (stripped) executables on many UNIX systems