perf subcmd: Create subcmd library

Move the subcommand-related files from perf to a new library named
libsubcmd.a.

Since we're moving files anyway, go ahead and rename 'exec_cmd.*' to
'exec-cmd.*' to be consistent with the naming of all the other files.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/c0a838d4c878ab17fee50998811612b2281355c1.1450193761.git.jpoimboe@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/Build

@@ -9,13 +9,10 @@ libperf-y += env.o
 libperf-y += event.o
 libperf-y += evlist.o
 libperf-y += evsel.o
-libperf-y += exec_cmd.o
 libperf-y += find_next_bit.o
-libperf-y += help.o
 libperf-y += kallsyms.o
 libperf-y += levenshtein.o
 libperf-y += llvm-utils.o
-libperf-y += parse-options.o
 libperf-y += parse-events.o
 libperf-y += perf_regs.o
 libperf-y += path.o
@@ -23,7 +20,6 @@ libperf-y += rbtree.o
 libperf-y += libstring.o
 libperf-y += bitmap.o
 libperf-y += hweight.o
-libperf-y += run-command.o
 libperf-y += quote.o
 libperf-y += strbuf.o
 libperf-y += string.o
@@ -32,11 +28,9 @@ libperf-y += strfilter.o
 libperf-y += top.o
 libperf-y += usage.o
 libperf-y += wrapper.o
-libperf-y += sigchain.o
 libperf-y += dso.o
 libperf-y += symbol.o
 libperf-y += color.o
-libperf-y += pager.o
 libperf-y += header.o
 libperf-y += callchain.o
 libperf-y += values.o
@@ -88,7 +82,6 @@ libperf-y += parse-branch-options.o
 libperf-y += parse-regs-options.o
 libperf-y += term.o
 libperf-y += help-unknown-cmd.o
-libperf-y += subcmd-config.o
 
 libperf-$(CONFIG_LIBBPF) += bpf-loader.o
 libperf-$(CONFIG_BPF_PROLOGUE) += bpf-prologue.o