Convert more wasi-libc code to //-style comments. (#153)

This is purely a style change, in accordance with #116.

dlmalloc/src/dlmalloc.c

@@ -1,74 +1,68 @@
-/*
+// This file is a wrapper around malloc.c, which is the upstream source file.
- * This file is a wrapper around malloc.c, which is the upstream source file.
+// It sets configuration flags and controls which symbols are exported.
- * It sets configuration flags and controls which symbols are exported.
- */
 
 #include <stddef.h>
 #include <malloc.h>
 
-/* Define configuration macros for dlmalloc. */
+// Define configuration macros for dlmalloc.
 
-/* WebAssembly doesn't have mmap-style memory allocation. */
+// WebAssembly doesn't have mmap-style memory allocation.
 #define HAVE_MMAP 0
 
-/* WebAssembly doesn't support shrinking linear memory. */
+// WebAssembly doesn't support shrinking linear memory.
 #define MORECORE_CANNOT_TRIM 1
 
-/* Disable sanity checks to reduce code size. */
+// Disable sanity checks to reduce code size.
 #define ABORT __builtin_unreachable()
 
-/* If threads are enabled, enable support for threads. */
+// If threads are enabled, enable support for threads.
 #ifdef _REENTRANT
 #define USE_LOCKS 1
 #endif
 
-/* Make malloc deterministic. */
+// Make malloc deterministic.
 #define LACKS_TIME_H 1
 
-/* Disable malloc statistics generation to reduce code size. */
+// Disable malloc statistics generation to reduce code size.
 #define NO_MALLINFO 1
 #define NO_MALLOC_STATS 1
 
-/* Align malloc regions to 16, to avoid unaligned SIMD accesses. */
+// Align malloc regions to 16, to avoid unaligned SIMD accesses.
 #define MALLOC_ALIGNMENT 16
 
-/*
+// Declare errno values used by dlmalloc. We define them like this to avoid
- * Declare errno values used by dlmalloc. We define them like this to avoid
+// putting specific errno values in the ABI.
- * putting specific errno values in the ABI.
- */
 extern const int __ENOMEM;
 #define ENOMEM __ENOMEM
 extern const int __EINVAL;
 #define EINVAL __EINVAL
 
-/*
+// Define USE_DL_PREFIX so that we leave dlmalloc's names prefixed with 'dl'.
- * Define USE_DL_PREFIX so that we leave dlmalloc's names prefixed with 'dl'.
+// We define them as "static", and we wrap them with public names below. This
- * We define them as "static", and we wrap them with public names below. This
+// serves two purposes:
- * serves two purposes:
+//
- *
+// One is to make it easy to control which symbols are exported; dlmalloc
- * One is to make it easy to control which symbols are exported; dlmalloc
+// defines several non-standard functions and we wish to explicitly control
- * defines several non-standard functions and we wish to explicitly control
+// which functions are part of our public-facing interface.
- * which functions are part of our public-facing interface.
+//
- *
+// The other is to protect against compilers optimizing based on the assumption
- * The other is to protect against compilers optimizing based on the assumption
+// that they know what functions with names like "malloc" do. Code in the
- * that they know what functions with names like "malloc" do. Code in the
+// implementation will call functions like "dlmalloc" and assume it can use
- * implementation will call functions like "dlmalloc" and assume it can use
+// the resulting pointers to access the metadata outside of the nominally
- * the resulting pointers to access the metadata outside of the nominally
+// allocated objects. However, if the function were named "malloc", compilers
- * allocated objects. However, if the function were named "malloc", compilers
+// might see code like that and assume it has undefined behavior and can be
- * might see code like that and assume it has undefined behavior and can be
+// optimized away. By using "dlmalloc" in the implementation, we don't need
- * optimized away. By using "dlmalloc" in the implementation, we don't need
+// -fno-builtin to avoid this problem.
- * -fno-builtin to avoid this problem.
- */
 #define USE_DL_PREFIX 1
 #define DLMALLOC_EXPORT static inline
 
-/* This isn't declared with DLMALLOC_EXPORT so make it static explicitly. */
+// This isn't declared with DLMALLOC_EXPORT so make it static explicitly.
 static size_t dlmalloc_usable_size(void*);
 
-/* Include the upstream dlmalloc's malloc.c. */
+// Include the upstream dlmalloc's malloc.c.
 #include "malloc.c"
 
-/* Export the public names. */
+// Export the public names.
 
 void *malloc(size_t size) {
     return dlmalloc(size);