gprofng: Use prototype to call libc functions

gprofng: Use prototype to call libc functions

libcollector may not link against libC.
We use dlsym() to get a function from libc.
In some files, pointers to these functions do not have prototypes.
I also moved the shared definitions to libcollector/collect.h.

gprofng/ChangeLog
2023-03-15  Vladimir Mezentsev  <vladimir.mezentsev@oracle.com>

	libcollector/collector.c: Add prototypes.
	libcollector/dispatcher.c: Likewise.
	libcollector/heaptrace.c: Likewise.
	libcollector/iotrace.c: Likewise.
	libcollector/linetrace.c: Likewise.
	libcollector/mmaptrace.c: Likewise.
	libcollector/synctrace.c: Likewise.
	libcollector/collector.h: Add CALL_REAL(), NULL_PTR(), and DBG_LT.