feat(headers): stddef/stdint/stdbool/limits/float/assert + features wiring

include/stdarg.h

@@ -0,0 +1,24 @@
+#ifndef VLIBC_STDARG_H
+#define VLIBC_STDARG_H
+
+/*
+ * vlibc — <stdarg.h>.
+ *
+ * Variable argument lists. The entire header defers to the compiler's
+ * builtin support: __builtin_va_list names the ABI's va_list layout and the
+ * __builtin_va_* entry points manipulate it. Nothing here depends on a
+ * system header.
+ *
+ * This header is ISO C core and is present in every profile.
+ */
+
+#include <vlibc/features.h>
+
+typedef __builtin_va_list va_list;
+
+#define va_start(ap, last) __builtin_va_start((ap), (last))
+#define va_end(ap) __builtin_va_end((ap))
+#define va_arg(ap, type) __builtin_va_arg((ap), type)
+#define va_copy(dst, src) __builtin_va_copy((dst), (src))
+
+#endif /* VLIBC_STDARG_H */