Update ccc driver  - Use CCC_ECHO to control echoing behavior (default is on, set to ''    or unset to disable)  - Get 'clang','llc','as','cc','ld' executables from environment. 'cc'    and 'ld' are fetched through CCC_CC and CCC_LD respectively -- to    support make CC=ccc -- the others are through their upcased    versions.  - Add CCC_NATIVE mode.    o This uses llc and as to generate native object files; allowing      more drop-in replacement of gcc.    o Disabled by default, but should eventually be default.    o Allow --emit-llvm in CCC_NATIVE mode to override. Essentially      this makes ccc more like a drop in replacement for llvm-gcc.  - Prevent explicit -x <language> options from annoying clang.
Update ccc driver
 - Use CCC_ECHO to control echoing behavior (default is on, set to ''
   or unset to disable)
 - Get 'clang','llc','as','cc','ld' executables from environment. 'cc'
   and 'ld' are fetched through CCC_CC and CCC_LD respectively -- to
   support make CC=ccc -- the others are through their upcased
   versions.
 - Add CCC_NATIVE mode.
   o This uses llc and as to generate native object files; allowing
     more drop-in replacement of gcc.
   o Disabled by default, but should eventually be default.
   o Allow --emit-llvm in CCC_NATIVE mode to override. Essentially
     this makes ccc more like a drop in replacement for llvm-gcc.
 - Prevent explicit -x <language> options from annoying clang.


git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@55260 91177308-0d34-0410-b5e6-96231b3b80d8

apple/swift-clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang