An automatic const char[] variable gets initialized at runtime, just
like any other automatic variable. For long strings, that uses a lot of
stack and wastes time building the string; e.g. for the "No %s
allocation events..." case one has:

  444516:       48 b8 4e 6f 20 25 73 20 61 6c   movabs $0x6c61207325206f4e,%rax # "No %s al"
  ...
  444674:       48 89 45 80                     mov    %rax,-0x80(%rbp)
  444678:       48 b8 6c 6f 63 61 74 69 6f 6e   movabs $0x6e6f697461636f6c,%rax # "location"
  444682:       48 89 45 88                     mov    %rax,-0x78(%rbp)
  444686:       48 b8 20 65 76 65 6e 74 73 20   movabs $0x2073746e65766520,%rax # " events "
  444690:       66 44 89 55 c4                  mov    %r10w,-0x3c(%rbp)
  444695:       48 89 45 90                     mov    %rax,-0x70(%rbp)
  444699:       48 b8 66 6f 75 6e 64 2e 20 20   movabs $0x20202e646e756f66,%rax

Make them all static so that the compiler just references objects in .rodata.

Committer testing:

Ok, using dwarves's codiff tool:

    $ codiff --functions /tmp/perf.before ~/bin/perf
  builtin-sched.c:
    cmd_sched                 |  -48
   1 function changed, 48 bytes removed, diff: -48

  builtin-report.c:
    cmd_report                |  -32
   1 function changed, 32 bytes removed, diff: -32

  builtin-kmem.c:
    cmd_kmem                  |  -64
    build_alloc_func_list     |  -50
   2 functions changed, 114 bytes removed, diff: -114

  builtin-c2c.c:
    perf_c2c__report          | -390
   1 function changed, 390 bytes removed, diff: -390

  ui/browsers/header.c:
    tui__header_window        | -104
   1 function changed, 104 bytes removed, diff: -104

  /home/acme/bin/perf:
   9 functions changed, 688 bytes removed, diff: -688
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20181102230624.20064-1-linux@rasmusvillemoes.dkSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>