top: raise the amount by which top's stat buffer grows

We won't go as far as the merge request shown below in
increasing buffer size, but we'll reduce substantially
total iterations while growing it to achieve one read.

[ and this seems in line with what was recently done ]
[ to accommodate the massively parallel environments ]
[ thru 2 abreast ('4') and combined cpus ('!') modes ]

Reference(s:
https://gitlab.com/procps-ng/procps/-/merge_requests/105

Signed-off-by: Jim Warner <james.warner@comcast.net>

top/top.c

@@ -2512,7 +2512,7 @@ static void cpus_refresh (void) {
    rewind(fp);
    fflush(fp);
 
- #define buffGRW 1024
+ #define buffGRW 8192
    /* we slurp in the entire directory thus avoiding repeated calls to fgets,
       especially in a massively parallel environment.  additionally, each cpu
       line is then frozen in time rather than changing until we get around to