superenv: support PPC bottles

Allows for building bottles on PPC both with and without Altivec.
This is currently not active but will be enabled once superenv is
stable on Leopard.

Library/ENV/4.3/cc

@@ -161,6 +161,10 @@ class Cmd
       args << '-march=core2'
     elsif cccfg? 'bi'
       args << '-march=prescott'
+    elsif cccfg? 'bpA'
+      args << '-mcpu=7400'
+    elsif cccfg? 'bp'
+      args << '-mcpu=750'
     else
       args << '-march=native' if tool =~ /clang/
     end

Library/Homebrew/extend/ENV/super.rb

@@ -85,6 +85,8 @@ module Superenv
     # b - Installing from a bottle
     # i - Installing from a bottle on Intel
     # 6 - Installing from a bottle on 64-bit Intel
+    # p - Installing from a bottle on PPC
+    # A - Installing from a bottle on PPC with Altivec
     # O - Enables argument refurbishing. Only active under the
     #     make/bsdmake wrappers currently.
     #
@@ -241,6 +243,12 @@ module Superenv
         else
           'bi'
         end
+      elsif Hardware::CPU.type == :ppc
+        if Hardware::CPU.altivec?
+          'bpA'
+        else
+          'bp'
+        end
       else
         'b'
       end