tree-optimization/109304 - properly handle instrumented aliases

When adjusting calls to reflect instrumentation we failed to handle
calls to aliases since they appear to have no body.  Instead resort
to symtab node availability.  The patch also avoids touching
internal function calls in a more obvious way (builtins might
have a body available).

profiledbootstrap & regtest running on x86_64-unknown-linux-gnu.

Honza - does this look OK?

	PR tree-optimization/109304
	* tree-profile.cc (tree_profiling): Use symtab node
	availability to decide whether to skip adjusting calls.
	Do not adjust calls to internal functions.

	* gcc.dg/pr109304.c: New testcase.