bin/archdep-filter: factored out

This code started breeding within pkg.in/*/Makefile,
and it was lacking both E2K (as a generic alias,
not just "e2k or e2kv4") _and_ the ability to negate
selection, as in "everywhere but not on any e2k").

Let's fix all of that at once, and parallelize sed
execution as well; my tests with 1000-line file
containing "a b c d@!E2K e@e2k f g@!X86 h i@IA32"
lines show roughly 3x higher CPU load and lower
execution time (~0.3 sec vs ~0.9 sec on 801-PC).

And turn that code snippet into a proper filter
with inline edit capability (I've dropped the exit
trap as failing to mv signals a disaster anyway).

bin/archdep-filter

@@ -0,0 +1,47 @@
+#!/bin/sh
+# filter stdin or file for words related to
+# the specified target architecture
+#
+# args: -a arch [-i file]
+
+if [ "$1" = "-a" -a -n "$2" ]; then
+	a="$2"
+	shift 2
+else
+	cat
+	exit
+fi
+
+if [ "$1" = "-i" -a -w "$2" ]; then
+	f="$2"
+	t="`mktemp`"
+fi
+
+# map meta-arches for prefiltering
+# NB: biarch gets special expansion later
+case "$a" in
+i586)
+	A="(IA32|X86)";;
+x86_64)
+	A="X86";;
+e2k*)
+	A="E2K";;
+*)
+	A=;;
+esac
+
+# NB: pipe runs in parallel => faster than -e -e
+cat ${f:+"$f"} |
+sed -rn "s/\<([^@ ]*)\>|\<([^@ ]*)@$A\>/\1\2/pg" |
+sed -rn "s/\<([^@ ]*)\>|\<[^@ ]*@\!$A\> */\1/pg" |
+sed -r  "s/\<([^@ ]*)@IA32\>/\1@i586 i586-\1@x86_64/g" |
+sed -rn "s/\<([^@ ]*)\>|\<([^@ ]*)@$a\>/\1\2/pg" |
+sed -rn "s/\<([^@ ]*)\>|\<[^@ ]*@\!$a\> */\1/pg" |
+sed -r  "s/\<([^@ ]*)@\![^@ ]+\>/\1/g" |
+sed -r  "s/\<([^@ ]*)@[^@ ]+\> *//g" |
+sed -r  "s/^ +//;s/ +$//" |
+if [ -n "$f" ]; then
+	cat > "$t" && mv "$t" "$f"
+else
+	cat
+fi