Fix compiler warnings:
v_utils.c:328:3: warning: passing argument 3 of ‘v_error’ discards ‘const’ qualifier from pointer target type [enabled by default]
In file included from v_utils.h:24:0,
from v_utils.c:24:
vgrabbj.h:285:24: note: expected ‘char *’ but argument is of type ‘const char *’
