add win32-specific explicit_bzero implementation

.gitignore

@@ -120,6 +120,7 @@ include/openssl/*.he
 !/crypto/Makefile.am.*
 !/crypto/compat/arc4random.h
 !/crypto/compat/b_win.c
+!/crypto/compat/explicit_bzero_win.c
 !/crypto/compat/posix_win.c
 !/crypto/compat/bsd_asprintf.c
 !/crypto/compat/inet_pton.c

crypto/Makefile.am

@@ -34,8 +34,12 @@ libcompatnoopt_la_CFLAGS = -O0
 libcompatnoopt_la_SOURCES =
 
 if !HAVE_EXPLICIT_BZERO
+if HOST_WIN
+libcompatnoopt_la_SOURCES += compat/explicit_bzero_win.c
+else
 libcompatnoopt_la_SOURCES += compat/explicit_bzero.c
 endif
+endif
 
 # other compatibility functions
 libcompat_la_SOURCES =

crypto/compat/explicit_bzero_win.c

@@ -0,0 +1,13 @@
+/*
+ * Public domain.
+ * Win32 explicit_bzero compatibility shim.
+ */
+
+#include <windows.h>
+#include <string.h>
+
+void
+explicit_bzero(void *buf, size_t len)
+{
+	SecureZeroMemory(buf, len);
+}