Makefile dep targets for cpp2 and util + dep update
Split out where() code and compiler attribute macros
cpp: show the location of an overridden macro
cpp: handle #line as well as #[0-9]
Moved common string functions from cpp/ to util/
cc1: #line directive handling
Added/fixed -xcpp-output for skipping preprocessing
cc1: track include nesting
cc1: update include stack line number when advancing
Added include nesting test
cpp: fit in with util/ backtrace on errors
cpp: fixed #warning/#error location
Option to not include the initial cc1 filename

For e.g. if we're from a ucc driver temporary file