Add profiling of CPU and memory usage (#912)

[rouault]

Extract from https://travis-ci.org/rouault/openjpeg/jobs/229438863 output :

Most CPU consuming functions:
Flat profile:
Each sample counts as 0.01 seconds.
  %   cumulative   self              self     total           
time   seconds   seconds    calls  ms/call  ms/call  name    
 29.85      0.20     0.20 15312165     0.00     0.00  opj_mqc_decode
 23.88      0.36     0.16    30595     0.01     0.01  opj_t1_dec_clnpass_generic
 14.93      0.46     0.10     9768     0.01     0.06  opj_t1_clbl_decode_processor
 11.94      0.54     0.08    24359     0.00     0.01  opj_t1_dec_refpass_mqc_generic
  4.48      0.57     0.03        3    10.00    13.33  opj_dwt_decode_real

Memory consumption profile:
n5: 182030675 (heap allocation functions) malloc/new/new[], --alloc-fns, etc.
 n2: 81687952 0x4E70F84: opj_malloc (opj_malloc.c:195)
  n1: 79970304 0x4E6E17A: opj_tcd_code_block_dec_allocate (tcd.c:1109)
   n1: 79970304 0x4E6DE30: opj_tcd_init_tile (tcd.c:1021)
    n1: 79970304 0x4E6E005: opj_tcd_init_decode_tile (tcd.c:1052)
     n1: 79970304 0x4E4B8C2: opj_j2k_read_tile_header (j2k.c:8132)
      n1: 79970304 0x4E500A3: opj_j2k_decode_tiles (j2k.c:9797)
       n1: 79970304 0x4E49BCE: opj_j2k_exec (j2k.c:7394)
        n1: 79970304 0x4E5091E: opj_j2k_decode (j2k.c:10023)
         n1: 79970304 0x4E5B576: opj_decode (openjpeg.c:430)
          n0: 79970304 0x413890: main (opj_decompress.c:1366)
  n0: 1717648 in 15 places, all below massif's threshold (01.00%)
 n3: 42844864 0x4E70FBE: opj_calloc (opj_malloc.c:203)
  n1: 38240256 0x4E4BE51: opj_j2k_update_image_data (j2k.c:8274)
   n1: 38240256 0x4E5023A: opj_j2k_decode_tiles (j2k.c:9832)
    n1: 38240256 0x4E49BCE: opj_j2k_exec (j2k.c:7394)
     n1: 38240256 0x4E5091E: opj_j2k_decode (j2k.c:10023)
      n1: 38240256 0x4E5B576: opj_decode (openjpeg.c:430)
       n0: 38240256 0x413890: main (opj_decompress.c:1366)
  n1: 3907200 0x4E6E1B1: opj_tcd_code_block_dec_allocate (tcd.c:1116)
   n1: 3907200 0x4E6DE30: opj_tcd_init_tile (tcd.c:1021)
    n1: 3907200 0x4E6E005: opj_tcd_init_decode_tile (tcd.c:1052)
     n1: 3907200 0x4E4B8C2: opj_j2k_read_tile_header (j2k.c:8132)
      n1: 3907200 0x4E500A3: opj_j2k_decode_tiles (j2k.c:9797)
       n1: 3907200 0x4E49BCE: opj_j2k_exec (j2k.c:7394)
        n1: 3907200 0x4E5091E: opj_j2k_decode (j2k.c:10023)
         n1: 3907200 0x4E5B576: opj_decode (openjpeg.c:430)
          n0: 3907200 0x413890: main (opj_decompress.c:1366)
  n0: 697408 in 34 places, all below massif's threshold (01.00%)
 n1: 38247412 0x4E70E50: opj_aligned_alloc_n (opj_malloc.c:61)
  n2: 38247412 0x4E70FDD: opj_aligned_malloc (opj_malloc.c:208)
   n1: 38240256 0x4E6C77E: opj_alloc_tile_component_data (tcd.c:624)
    n1: 38240256 0x4E6CDE6: opj_tcd_init_tile (tcd.c:757)
     n1: 38240256 0x4E6E005: opj_tcd_init_decode_tile (tcd.c:1052)
      n1: 38240256 0x4E4B8C2: opj_j2k_read_tile_header (j2k.c:8132)
       n1: 38240256 0x4E500A3: opj_j2k_decode_tiles (j2k.c:9797)
        n1: 38240256 0x4E49BCE: opj_j2k_exec (j2k.c:7394)
         n1: 38240256 0x4E5091E: opj_j2k_decode (j2k.c:10023)
          n1: 38240256 0x4E5B576: opj_decode (openjpeg.c:430)
           n0: 38240256 0x413890: main (opj_decompress.c:1366)
   n0: 7156 in 4 places, all below massif's threshold (01.00%)
 n2: 19249879 0x4E71051: opj_realloc (opj_malloc.c:234)
  n1: 19120128 0x4E500E8: opj_j2k_decode_tiles (j2k.c:9815)
   n1: 19120128 0x4E49BCE: opj_j2k_exec (j2k.c:7394)
    n1: 19120128 0x4E5091E: opj_j2k_decode (j2k.c:10023)
     n1: 19120128 0x4E5B576: opj_decode (openjpeg.c:430)
      n0: 19120128 0x413890: main (opj_decompress.c:1366)
  n0: 129751 in 2 places, all below massif's threshold (01.00%)
 n0: 568 in 1 place, below massif's threshold (01.00%)