Fix token pasting with -ftrack-macro-expansion

Fix token pasting with -ftrack-macro-expansion

This patch makes token pasting work with -ftrack-macro-expansion
turned on.  It improves some pasting related tests of the gcc.dg/cpp
subdirectory.

Tested and bootstrapped on x86_64-unknown-linux-gnu against trunk.

Note that the bootstrap with -ftrack-macro-expansion exhibits other
separate issues that are addressed in subsequent patches.  This patch
just fixes one class of problems.

The patch does pass bootstrap with -ftrack-macro-expansion turned off,
though.

libcpp/

	* macro.c (paste_all_tokens): Put the token resulting from pasting
	into an extended token context with -ftrack-macro-location is in
	effect.

gcc/testsuite/

	* gcc.dg/cpp/paste17.c: New test case for
	-ftrack-macro-expansion=2 mode only.
	* gcc.dg/cpp/macro-exp-tracking-5.c: Likewise.

From-SVN: r186966