Fixes Homebrew/homebrew#1115 for Ruby 1.9, thanks to assaf.

* Reorder a flag
* Don't show values if they are empty

This allows more complicated transformations to happen,
such as stripping out part of the variable.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>

Signed-off-by: Adam Vandenberg <flangy@gmail.com>

Signed-off-by: Adam Vandenberg <flangy@gmail.com>

* Adds GCC 4.0 version info to --config output.
* Splits gcc_build into gcc_40_build and gcc_42_build.
* Adds alias gcc_build to gcc_42_build for compatibility.
* Updates Xcode checking to also check GCC 4.0 version.

These changes are a combination of work by AdamV and my work
on my Tiger branch. This information would be useful for all
installs since some formulae compile with GCC 4.0.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>

Signed-off-by: Adam Vandenberg <flangy@gmail.com>

If /usr/local doesn't exist you've just sudo chowned $PWD

It's nice that smaller READMEs are easier to get right.

Removed requirements. If they want to know this stuff then read the verbose instructions. Or just try to run brew, it'll complain.

* Removed use of String altogether since all use cases
  are Arrays currently. YAGNI.

* #max_by would have been more elegant, but this way we
  can support 1.8.6.

Signed-off-by: Max Howell <max@methylblue.com>

I made the diff less gratuitous. Don't bloat diffs to meet personal coding style preferences :P

Closes Homebrew/homebrew#896