[PATCH v6 0/2] less: fully implement -R

[FriendlyNeighborhoodShane]

The switch was half-implemented earlier and it only used to trim escape
sequences. This patch series implements the feature fully i.e. makes
it emit color (SGR) sequences raw, and fixes other behaviour around it.

function                                             old     new   delta
buffer_print                                         734     893    +159
.rodata                                           100509  100527     +18
packed_usage                                       34508   34506      -2
read_lines                                           896     810     -86
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/2 up/down: 177/-88)            Total: 89 bytes

Changes from v5:
 - fix build warnings with the config turned off
 - reduce size cost of patch with config turned off, at cost of a little
   more size with it turned on.

Changes from v4:
 - replace strspn with manual loop for size reduction
 - fix formatting mistakes

Changes from v3:
 - fixed regex in commit message

Changes from v2:
 - fixed corrupted patches (accidentally edited before sending)
 - fix code style

Changes from v1:
 - count_colctrl does better validation for SGR sequences