Fixes various warnings noticed on Windows (#425)

* Fixes various warnings noticed on Windows

- Adds a prototype for our implementation of vasprintf
- Return type of H5_get_utf16_str() is now non-const
- Fixes possible uninitialized return type in Wremove_utf8
- Better isolation of fork() code in accum.c:test_swmr_write_big()
- Better isolation of non-zlib code in dsets.c:test_filter_delete()
- Removed unused variable in trefer.c:test_reference_cmpnd_obj()

* Fixes clang-format issues

3 files changed, 15 insertions, 12 deletions

diff --git a/src/H5private.h b/src/H5private.h
index 741214f..64ab988 100644
--- a/src/H5private.h
+++ b/src/H5private.h
@@ -675,11 +675,6 @@ typedef struct {
 #ifndef HDacos
 #define HDacos(X) acos(X)
 #endif /* HDacos */
-#ifndef HDvasprintf
-#ifdef H5_HAVE_VASPRINTF
-#define HDvasprintf(RET, FMT, A) vasprintf(RET, FMT, A)
-#endif /* H5_HAVE_VASPRINTF */
-#endif /* HDvasprintf */
 #ifndef HDalarm
 #ifdef H5_HAVE_ALARM
 #define HDalarm(N) alarm(N)
@@ -1647,6 +1642,13 @@ H5_DLL int64_t HDstrtoll(const char *s, const char **rest, int base);
 #ifndef HDutime
 #define HDutime(S, T) utime(S, T)
 #endif /* HDutime */
+#ifndef HDvasprintf
+#ifdef H5_HAVE_VASPRINTF
+#define HDvasprintf(RET, FMT, A) vasprintf(RET, FMT, A)
+#else
+H5_DLL int     HDvasprintf(char **bufp, const char *fmt, va_list _ap);
+#endif /* H5_HAVE_VASPRINTF */
+#endif /* HDvasprintf */
 #ifndef HDva_arg
 #define HDva_arg(A, T) va_arg(A, T)
 #endif /* HDva_arg */
diff --git a/src/H5system.c b/src/H5system.c
index 2ac3f93..53307a8 100644
--- a/src/H5system.c
+++ b/src/H5system.c
@@ -66,7 +66,7 @@
 /* Track whether tzset routine was called */
 static hbool_t H5_ntzset = FALSE;
 
-#ifndef HDvasprintf
+#ifndef H5_HAVE_VASPRINTF
 /* HDvasprintf provides vasprintf-like function on targets where it is
  * unavailable.
  */
@@ -94,7 +94,7 @@ HDvasprintf(char **bufp, const char *fmt, va_list _ap)
     }
     return -1;
 }
-#endif
+#endif /* H5_HAVE_VASPRINTF */
 
 /*-------------------------------------------------------------------------
  * Function:  HDstrtoll
@@ -737,7 +737,7 @@ Wroundf(float arg)
  *
  *-------------------------------------------------------------------------
  */
-const wchar_t *
+wchar_t *
 H5_get_utf16_str(const char *s)
 {
     int      nwchars = -1;   /* Length of the UTF-16 buffer */
@@ -833,7 +833,7 @@ int
 Wremove_utf8(const char *path)
 {
     wchar_t *wpath = NULL; /* UTF-16 version of the path */
-    int      ret;
+    int      ret   = -1;
 
     /* Convert the input UTF-8 path to UTF-16 */
     if (NULL == (wpath = H5_get_utf16_str(path)))
diff --git a/src/H5win32defs.h b/src/H5win32defs.h
index b4b253f..8f3947a 100644
--- a/src/H5win32defs.h
+++ b/src/H5win32defs.h
@@ -176,9 +176,10 @@ H5_DLL int    c99_snprintf(char *str, size_t size, const char *format, ...);
 H5_DLL int    c99_vsnprintf(char *str, size_t size, const char *format, va_list ap);
 H5_DLL int    Wnanosleep(const struct timespec *req, struct timespec *rem);
 H5_DLL herr_t H5_expand_windows_env_vars(char **env_var);
-H5_DLL const wchar_t *H5_get_utf16_str(const char *s);
-H5_DLL int            Wopen_utf8(const char *path, int oflag, ...);
-H5_DLL int            Wremove_utf8(const char *path);
+H5_DLL wchar_t *H5_get_utf16_str(const char *s);
+H5_DLL int      Wopen_utf8(const char *path, int oflag, ...);
+H5_DLL int      Wremove_utf8(const char *path);
+H5_DLL int      H5_get_win32_times(H5_timevals_t *tvs);
 
 /* Round functions only needed for VS2012 and earlier.
  * They are always built to ensure they don't go stale and