perf annotate: Propagate perf_env__arch() error

The callers of symbol__annotate2() use symbol__strerror_disassemble() to
convert its failure returns into a human readable string, so
propagate error values from functions it calls, starting with
perf_env__arch() that when fails the right thing to do is to look at
'errno' to see why its possible call to uname() failed.

Reported-by: Russell King - ARM Linux admin <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>,
Cc: Will Deacon <[e-mail]>
Link: https://lkml.kernel.org/n/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/annotate.c

···
 	int err;
 
 	if (!arch_name)
-		return -1;
+		return errno;
 
 	args.arch = arch = arch__find(arch_name);
 	if (arch == NULL)