tree-sitter: vendor tree-sitter runtime

tree-sitter/tree-sitter commit 7685b7861ca475664b6ef57e14d1da9acf741275

Included files are:
lib/include/tree-sitter/*.h
lib/src/*.[ch]
LICENSE

src/tree_sitter/atomic.h

@@ -0,0 +1,42 @@
+#ifndef TREE_SITTER_ATOMIC_H_
+#define TREE_SITTER_ATOMIC_H_
+
+#include <stdint.h>
+
+#ifdef _WIN32
+
+#include <windows.h>
+
+static inline size_t atomic_load(const volatile size_t *p) {
+  return *p;
+}
+
+static inline uint32_t atomic_inc(volatile uint32_t *p) {
+  return InterlockedIncrement(p);
+}
+
+static inline uint32_t atomic_dec(volatile uint32_t *p) {
+  return InterlockedDecrement(p);
+}
+
+#else
+
+static inline size_t atomic_load(const volatile size_t *p) {
+#ifdef __ATOMIC_RELAXED
+  return __atomic_load_n(p, __ATOMIC_RELAXED);
+#else
+  return __sync_fetch_and_add((volatile size_t *)p, 0);
+#endif
+}
+
+static inline uint32_t atomic_inc(volatile uint32_t *p) {
+  return __sync_add_and_fetch(p, 1u);
+}
+
+static inline uint32_t atomic_dec(volatile uint32_t *p) {
+  return __sync_sub_and_fetch(p, 1u);
+}
+
+#endif
+
+#endif  // TREE_SITTER_ATOMIC_H_