tools lib subcmd: Use str_error_r()

To make it portable to non-glibc systems, that follow the XSI variant
instead of the GNU specific one that gets in place when _GNU_SOURCE is
defined.

Cc: Adrian Hunter <[e-mail]>
Cc: David Ahern <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Josh Poimboeuf <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Steven Rostedt <[e-mail]>
Cc: Wang Nan <[e-mail]>
Link: http://lkml.kernel.org/n/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/lib/subcmd/run-command.c

···
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <string.h>
+#include <linux/string.h>
 #include <errno.h>
 #include <sys/wait.h>
 #include "subcmd-util.h"
···
 
 		if (cmd->dir && chdir(cmd->dir))
 			die("exec %s: cd to %s failed (%s)", cmd->argv[0],
-			    cmd->dir, strerror_r(errno, sbuf, sizeof(sbuf)));
+			    cmd->dir, str_error_r(errno, sbuf, sizeof(sbuf)));
 		if (cmd->env) {
 			for (; *cmd->env; cmd->env++) {
 				if (strchr(*cmd->env, '='))
···
 			if (errno == EINTR)
 				continue;
 			fprintf(stderr, " Error: waitpid failed (%s)",
-				strerror_r(errno, sbuf, sizeof(sbuf)));
+				str_error_r(errno, sbuf, sizeof(sbuf)));
 			return -ERR_RUN_COMMAND_WAITPID;
 		}
 		if (waiting != pid)

tools/objtool/Build

···
 objtool-y += objtool.o
 
 objtool-y += libstring.o
+objtool-y += str_error_r.o
 
 CFLAGS += -I$(srctree)/tools/lib
 
 $(OUTPUT)libstring.o: ../lib/string.c FORCE
+	$(call rule_mkdir)
+	$(call if_changed_dep,cc_o_c)
+
+$(OUTPUT)str_error_r.o: ../lib/str_error_r.c FORCE
 	$(call rule_mkdir)
 	$(call if_changed_dep,cc_o_c)