Disentangle assert and util

This is the first header refactoring diff, #533.  It splits the assert and util
components into separate, hermetic, header files.  In the process, it splits out
two of the large sub-components of util (the stdio.h replacement, and bit
manipulation routines) into their own components (malloc_io.h and bit_util.h).
This is mostly to break up cyclic dependencies, but it also breaks off a good
chunk of the catch-all-ness of util, which is nice.

include/jemalloc/internal/util.h

@@ -0,0 +1,71 @@
+#ifndef JEMALLOC_INTERNAL_UTIL_H
+#define JEMALLOC_INTERNAL_UTIL_H
+
+#define UTIL_INLINE static inline
+
+/* Junk fill patterns. */
+#ifndef JEMALLOC_ALLOC_JUNK
+#  define JEMALLOC_ALLOC_JUNK	((uint8_t)0xa5)
+#endif
+#ifndef JEMALLOC_FREE_JUNK
+#  define JEMALLOC_FREE_JUNK	((uint8_t)0x5a)
+#endif
+
+/*
+ * Wrap a cpp argument that contains commas such that it isn't broken up into
+ * multiple arguments.
+ */
+#define JEMALLOC_ARG_CONCAT(...) __VA_ARGS__
+
+/* cpp macro definition stringification. */
+#define STRINGIFY_HELPER(x) #x
+#define STRINGIFY(x) STRINGIFY_HELPER(x)
+
+/*
+ * Silence compiler warnings due to uninitialized values.  This is used
+ * wherever the compiler fails to recognize that the variable is never used
+ * uninitialized.
+ */
+#ifdef JEMALLOC_CC_SILENCE
+#  define JEMALLOC_CC_SILENCE_INIT(v) = v
+#else
+#  define JEMALLOC_CC_SILENCE_INIT(v)
+#endif
+
+#ifdef __GNUC__
+#  define likely(x)   __builtin_expect(!!(x), 1)
+#  define unlikely(x) __builtin_expect(!!(x), 0)
+#else
+#  define likely(x)   !!(x)
+#  define unlikely(x) !!(x)
+#endif
+
+#if !defined(JEMALLOC_INTERNAL_UNREACHABLE)
+#  error JEMALLOC_INTERNAL_UNREACHABLE should have been defined by configure
+#endif
+
+#define unreachable() JEMALLOC_INTERNAL_UNREACHABLE()
+
+/* Set error code. */
+UTIL_INLINE void
+set_errno(int errnum) {
+#ifdef _WIN32
+	SetLastError(errnum);
+#else
+	errno = errnum;
+#endif
+}
+
+/* Get last error code. */
+UTIL_INLINE int
+get_errno(void) {
+#ifdef _WIN32
+	return GetLastError();
+#else
+	return errno;
+#endif
+}
+
+#undef UTIL_INLINE
+
+#endif /* JEMALLOC_INTERNAL_UTIL_H */