[libc] Add new libc

This new libc is mostly from scratch, with *printf() functions provided
by Marco Paland and Eyal Rozenberg's tiny printf library, and malloc and
friends provided by dlmalloc.

src/libraries/libc/limits.h

@@ -0,0 +1,84 @@
+#pragma once
+/** \file limits.h
+  * Sizes of integer types
+  *
+  * This file is part of the C standard library for the jsix operating
+  * system.
+  *
+  * This Source Code Form is subject to the terms of the Mozilla Public
+  * License, v. 2.0. If a copy of the MPL was not distributed with this
+  * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+  */
+
+#define CHAR_BIT     __CHAR_BIT__
+
+#define SCHAR_MAX    __SCHAR_MAX__
+#define SCHAR_MIN    ((-__SCHAR_MAX__) - 1)
+#define UCHAR_MAX    __UCHAR_MAX__
+
+#if ((char)-1) < 0
+// char is signed
+#define CHAR_MAX     SCHAR_MAX
+#define CHAR_MIN     SCHAR_MIN
+#else
+// char is unsigned
+#define CHAR_MAX     UCHAR_MAX
+#define CHAR_MIN     0
+#endif
+
+#define MB_LEN_MAX
+
+#define SHRT_MAX     __SHRT_MAX__
+#define SHRT_MIN     ((-__SHRT_MAX__) - 1)
+
+#if __SIZEOF_SHORT__ == 1
+#define USHRT_MAX    __UINT8_MAX__
+#elif __SIZEOF_SHORT__ == 2
+#define USHRT_MAX    __UINT16_MAX__
+#elif __SIZEOF_SHORT__ == 4
+#define USHRT_MAX    __UINT32_MAX__
+#endif
+
+#define INT_MAX      __INT_MAX__
+#define INT_MIN      ((-__INT_MAX__) - 1)
+
+#if __SIZEOF_INT__ == 1
+#define UINT_MAX     __UINT8_MAX__
+#elif __SIZEOF_INT__ == 2
+#define UINT_MAX     __UINT16_MAX__
+#elif __SIZEOF_INT__ == 4
+#define UINT_MAX     __UINT32_MAX__
+#elif __SIZEOF_INT__ == 8
+#define UINT_MAX     __UINT64_MAX__
+#endif
+
+#define LONG_MAX     __LONG_MAX__
+#define LONG_MIN     ((-__LONG_MAX__) - 1)
+
+#if __SIZEOF_LONG__ == 1
+#define ULONG_MAX    __UINT8_MAX__
+#elif __SIZEOF_LONG__ == 2
+#define ULONG_MAX    __UINT16_MAX__
+#elif __SIZEOF_LONG__ == 4
+#define ULONG_MAX    __UINT32_MAX__
+#elif __SIZEOF_LONG__ == 8
+#define ULONG_MAX    __UINT64_MAX__
+#elif __SIZEOF_LONG__ == 16
+#define ULONG_MAX    __UINT128_MAX__
+#endif
+
+#define LLONG_MAX    __LONG_LONG_MAX__
+#define LLONG_MIN    ((-__LONG_LONG_MAX__) - 1)
+
+#if __SIZEOF_LONG_LONG__ == 1
+#define ULLONG_MAX   __UINT8_MAX__
+#elif __SIZEOF_LONG_LONG__ == 2
+#define ULLONG_MAX   __UINT16_MAX__
+#elif __SIZEOF_LONG_LONG__ == 4
+#define ULLONG_MAX   __UINT32_MAX__
+#elif __SIZEOF_LONG_LONG__ == 8
+#define ULLONG_MAX   __UINT64_MAX__
+#elif __SIZEOF_LONG_LONG__ == 16
+#define ULLONG_MAX   __UINT128_MAX__
+#endif
+