Enable optionally using libc++ on OS X (when targeting 10.7 or later)

Experimental work in progress.

Change-Id: I92663e07c7322037182141603f72c6d442da6ee9
Look for the 10.9 SDK, too

Change-Id: Iee70f531422fe6a312830dc9aa2d57e4f802953d
Simplify EPM tests for OS X

We always should use the internal epm anyway on OS X, so no need to
look for PackageMaker.app in /Developer which doesn't even exist any
more.

Change-Id: I943f34e14e9ce0c3bec5bd7b86612a62e5b9e83d
Don't use -d32 when building 64-bit code

Change-Id: I83a960cebb8347170a08d2fda7ed11050b8c4229
Do not silently ignore --enable-libc++
Enforce avoiding looking for non-existent system dicts on OS X and Windows

It is totally pointless to look for "system" /usr/share/myspell,
hyphen and mythes dictionaries on systems where they don't exist. Use
only bundled dictionaries.

(For OS X, we have code to use a system-specific spell checking API.)

Change-Id: I13aed7225d003e608f61de95671feb2e50b26c25
Stop defining "inline" as empty on OS X and iOS in icu

It causes problems on newer SDKs.

Change-Id: I6bdb1e50cb239d99b190460fdb11d5c684e92275
Use IOKit *framework*, not library directly. And ApplicationServices

Change-Id: I6e67bb5a4c540d0be605c54c833ebb0b4187c771