Don't share as, ncg, top between Linux and Mac OS X.

Telling osx386 and osxppc to build and run their own tools, not to
reuse the tools from linux386 and linuxppc.  This wastes time to build
identical tools, but it removes some bogus dependencies.  OS X tools
had wrongly depended on Linux descr files and aelflod; now they don't.

Discussion in https://github.com/davidgiven/ack/pull/23

plat/osx386/build-tools.lua

@@ -1,8 +1,21 @@
+include("plat/build.lua")
+
+build_as {
+	name = "as",
+	arch = "i386",
+}
+
+build_ncg {
+	name = "ncg",
+	arch = "i386",
+}
+
 return installable {
 	name = "tools",
 	map = {
+		["$(PLATDEP)/osx386/as"] = "+as",
+		["$(PLATDEP)/osx386/ncg"] = "+ncg",
 		["$(PLATIND)/descr/osx386"] = "./descr",
-		"plat/linux386+tools",
 		"plat/osx/cvmach+pkg",
 		"util/opt+pkg",
 	}

plat/osx386/descr

@@ -34,7 +34,7 @@ var C_INCLUDES=-I{EM}/share/ack/osx/include -I{EM}/share/ack/include/ansi
 name be
 	from .m.g
 	to .s
-	program {EM}/lib/ack/linux386/ncg
+	program {EM}/lib/ack/{PLATFORM}/ncg
 	mapflag -gdb GF=-gdb
 	args {GF?} <
 	stdout
@@ -43,7 +43,7 @@ end
 name as
 	from .s.so
 	to .o
-	program {EM}/lib/ack/linux386/as
+	program {EM}/lib/ack/{PLATFORM}/as
 	args - -o > <
 	prep cond
 end

plat/osxppc/build-tools.lua

@@ -1,8 +1,27 @@
+include("plat/build.lua")
+
+build_as {
+	name = "as",
+	arch = "powerpc",
+}
+
+build_ncg {
+	name = "ncg",
+	arch = "powerpc",
+}
+
+build_top {
+	name = "top",
+	arch = "powerpc",
+}
+
 return installable {
 	name = "tools",
 	map = {
+		["$(PLATDEP)/osxppc/as"] = "+as",
+		["$(PLATDEP)/osxppc/ncg"] = "+ncg",
+		["$(PLATDEP)/osxppc/top"] = "+top",
 		["$(PLATIND)/descr/osxppc"] = "./descr",
-		"plat/linuxppc+tools",
 		"plat/osx/cvmach+pkg",
 		"util/opt+pkg",
 	}

plat/osxppc/descr

@@ -30,7 +30,7 @@ var C_INCLUDES=-I{EM}/share/ack/osx/include -I{EM}/share/ack/include/ansi
 name be
 	from .m.g
 	to .s
-	program {EM}/lib/ack/linuxppc/ncg
+	program {EM}/lib/ack/{PLATFORM}/ncg
 	mapflag -gdb GF=-gdb
 	args {GF?} <
 	stdout
@@ -39,7 +39,7 @@ end
 name asopt
 	from .s
 	to .so
-	program {EM}/lib/ack/linuxppc/top
+	program {EM}/lib/ack/{PLATFORM}/top
 	args
 	optimizer
 	stdin
@@ -48,7 +48,7 @@ end
 name as
 	from .s.so
 	to .o
-	program {EM}/lib/ack/linuxppc/as
+	program {EM}/lib/ack/{PLATFORM}/as
 	args - -o > <
 	prep cond
 end