perf tools: Move strlcpy() from perf to tools/lib/string.c

perf tools: Move strlcpy() from perf to tools/lib/string.c

strlcpy() will be needed by the subcmd library.  Move it to the shared
tools/lib/string.c file which can be used by other tools.

Signed-off-by: Josh Poimboeuf <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/71e2804b973bf39ad3d3b9be10f99f2ea630be46.1450193761.git.jpoimboe@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>