[acme] "values unreachable" warnings in acme.g4.

[kaby76]

While checking out a full build of grammars-v4 with the Rust target, I noticed warnings outputted from the Antlr Tool for the acme grammar.

warning(184): acme.g4:886:0: One of the token PATHSEPARATOR values unreachable. : is always overlapped by token COLON
warning(184): acme.g4:886:0: One of the token PATHSEPARATOR values unreachable. . is always overlapped by token DOT
warning(184): acme.g4:886:0: One of the token PATHSEPARATOR values unreachable. - is always overlapped by token MINUS
warning(184): acme.g4:910:0: One of the token PLUS values unreachable. + is always overlapped by token PATHSEPARATOR
warning(184): acme.g4:946:0: One of the token REM values unreachable. % is always overlapped by token PATHSEPARATOR
warning(184): acme.g4:987:0: One of the token SLASH values unreachable. / is always overlapped by token PATHSEPARATOR
warning(184): acme.g4:886:0: One of the token PATHSEPARATOR values unreachable. : is always overlapped by token COLON
warning(184): acme.g4:886:0: One of the token PATHSEPARATOR values unreachable. . is always overlapped by token DOT
warning(184): acme.g4:886:0: One of the token PATHSEPARATOR values unreachable. - is always overlapped by token MINUS
warning(184): acme.g4:910:0: One of the token PLUS values unreachable. + is always overlapped by token PATHSEPARATOR
warning(184): acme.g4:946:0: One of the token REM values unreachable. % is always overlapped by token PATHSEPARATOR
warning(184): acme.g4:987:0: One of the token SLASH values unreachable. / is always overlapped by token PATHSEPARATOR

PATHSEPARATOR was mentioned before in #2308. A fix was suggested in ispras@3c3b17d. But, it doesn't look correct, and was never merged.