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

1 files changed, 4 insertions, 4 deletions

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)))