Buffer overrun in TclCompileTokens()

Bug found in Tcl 8.4a4, but also in 8.3.

Reproductible script:

proc bug {} {
puts $array([expr {a+2}])
}

In generic/tclCompile.c, function TclCompileTokens(),
line 1242:

sprintf(buffer,
"\n (parsing index for array \"%.*s\")",
((nameBytes > 100)? 100 : nameBytes), name);

but buffer is large enough to contains TCL_UTF_MAX :(.