Fix some issues with building the project on macos

[ddickstein]

Fixes a couple issues I ran into when building the project on macos:

1. Without the \ in the SONAME_MINOR line, make failed with:

/Library/Developer/CommandLineTools/usr/bin/make -C grammars/ocaml all
../../common/common.mak:39: *** unterminated call to function `shell': missing `)'.  Stop.
make: *** [all] Error 2

with the \, the replacement still seems to work (at least on macos).
2. Depend directly on grammar.js instead of grammar.json, which is itself generated from grammar.js. This ensures that modifications to grammar.js get reflected in the parser without you needing to remember to separately call make generate.

[314eter]

Since this file is based on the tree-sitter template, it's best to open a PR there first.

[ObserverOfTime]

Revert this. Running make should not require Node.js, which generating from grammar.js does.

[ddickstein]

@ObserverOfTime Isn't it worse to allow grammar.js to fall out of sync than to require node be installed? It's a real dependency of the build process. For what it's worth, I spent a non-trivial amount of time trying to figure out why my changes weren't being taking effect - I generally expect make to build the product from the latest source.

[314eter]

Similar to how cargo build, go build and npm install are compiling/building language bindings, make is compiling the C bindings. They're doing that under the assumption that the parser.c files are already generated, so they don't force npm and tree-sitter dependencies on everyone.

I think this whole rule should be removed, since it introduces a dependency on the tree-sitter executable.