tree-sitter-grammar.eclass: force use of local parser.h

There shouldn't be a system-wide copy of parser.h and upstream plan on
dropping this from dev-libs/tree-sitter as it can cause issues if there's
a mismatch between the version used for the bundled generated parser
vs the header used to build the library.

Force use of the correct one in the dist tarball at src/tree_sitter/parser.h
instead. Drop the dependency on dev-libs/tree-sitter given we were only depending
on it for this header.

Bug: tree-sitter/tree-sitter-bash#199
Bug: https://bugs.gentoo.org/912716
Signed-off-by: Sam James <sam@gentoo.org>

eclass/tree-sitter-grammar.eclass

@@ -24,9 +24,6 @@ SRC_URI="https://github.com/tree-sitter/${PN}/archive/${TS_PV:-v${PV}}.tar.gz
 	-> ${P}.tar.gz"
 S="${WORKDIR}"/${PN}-${TS_PV:-${PV}}/src
 
-# Needed for tree_sitter/parser.h
-DEPEND="dev-libs/tree-sitter"
-
 BDEPEND+=" test? ( dev-util/tree-sitter-cli )"
 IUSE+=" test"
 RESTRICT+=" !test? ( test )"
@@ -61,8 +58,10 @@ tree-sitter-grammar_src_compile() {
 	# or scanner.cc.
 
 	tc-export CC CXX
-	export CFLAGS="${CFLAGS} -fPIC"
-	export CXXFLAGS="${CXXFLAGS} -fPIC"
+	# We want to use the bundled parser.h, not anything lurking on the system, hence -I
+	# See https://github.com/tree-sitter/tree-sitter-bash/issues/199#issuecomment-1694416505
+	export CFLAGS="${CFLAGS} -fPIC -I. -Itree_sitter"
+	export CXXFLAGS="${CXXFLAGS} -fPIC -I. -Itree_sitter"
 
 	local objects=( parser.o )
 	if [[ -f "${S}"/scanner.c || -f "${S}"/scanner.cc ]]; then