Update to 1.2.0

Changes from 1.1.0 to 1.2.0:

• Features:
  • new --path option lists the .pc files which provided the requested dependencies
  • new path relocation API: pkgconf_path_relocate(), which wraps functions such as realpath() and cygwin_conv_path().
  • new --with-path option adds a path to the search list
  • new --define-prefix and --dont-define-prefix features enable automatic prefix detection for relocatable SDKs. this is mostly useful on windows.

• Bug fixes:
  • fragments: fix even more edge cases involving token concatenation
  • path lists: don't attempt to collect path inodes if the filter is disabled
  • path lists: explicitly avoid uninitialised data for the path inode cache
  • client: properly handle --keep-system-cflags and --keep-system-libs

• Enhancements:
  • windows: build libpkgconf as a DLL
  • fragments: only munge fragments if sysroot_dir is actually set
  • overall API: resolver flags have been moved to being a client-object setting instead of used for every function invocation