perf tools: Ditch rtrim(), use strim() from tools/lib

Cleaning up a bit more tools/perf/util/ by using things we got from the
kernel and have in tools/lib/

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-7hluuoveryoicvkclshzjf1k@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/string.c

@@ -318,29 +318,6 @@ char *strxfrchar(char *s, char from, char to)
 	return s;
 }
 
-/**
- * rtrim - Removes trailing whitespace from @s.
- * @s: The string to be stripped.
- *
- * Note that the first trailing whitespace is replaced with a %NUL-terminator
- * in the given string @s. Returns @s.
- */
-char *rtrim(char *s)
-{
-	size_t size = strlen(s);
-	char *end;
-
-	if (!size)
-		return s;
-
-	end = s + size - 1;
-	while (end >= s && isspace(*end))
-		end--;
-	*(end + 1) = '\0';
-
-	return s;
-}
-
 char *asprintf_expr_inout_ints(const char *var, bool in, size_t nints, int *ints)
 {
 	/*