Gcov and PGO

[Peter Davies]

After applying my "[RESEND 2] Changes to enable the use of gcov and PGO" patch
To use gcov:
   Run "make EXTRACFLAGS=--coverage LDFLAGS=--coverage"
   Run program (presumably test suite)
   Run "gcov file.c" (multiple files like "gcov *.c" doesn't work for
some reason)
To use PGO
   Run "make EXTRACFLAGS=-fprofile-generate LDFLAGS=-fprofile-generate"
   Run sample program (test suite is inappropriate because it doesn't
represent normal usage).
   Run "make clean"
   Run "make EXTRACFLAGS=-fprofile-use LDFLAGS=-fprofile-use"

Peter