Syntax error in caller.def

[Roland Illig]

static char *caller_doc[] = {
N_("Returns the context of the current subroutine call.\n\
    \n\
    Without EXPR, returns "$line $filename".  With EXPR, returns\n\
    "$line $subroutine $filename"; this extra information can be used to\n\
    provide a stack trace.\n\
    \n\
    The value of EXPR indicates how many call frames to go back before
the\n\
    current one; the top frame is frame 0."),
  (char *)NULL
};

The "$line $subroutine $filename" part looks good to humans, but the C
compiler should reject it since the string actually ends at the " before
$line.

According to examples/loadables/Makefile.in, caller.def is not compiled
with LOADABLE_BUILTIN defined, which explains why the bug has not failed
the build.