Avoid C99 feature to fix build with Embarcadero's XE7 compiler.

Based on patch by Boaz Stolk <bstolk@aweta.nl>.

lib/zip_source_win32a.c

diff --git a/lib/zip_source_win32a.c b/lib/zip_source_win32a.c
index ac1f256..2d339cb 100644
--- a/lib/zip_source_win32a.c
+++ b/lib/zip_source_win32a.c
@@ -44,11 +44,11 @@
 static int _win32_remove_a(const void *fname);
 
 static _zip_source_win32_file_ops_t win32_ops_a = {
-    .op_strdup         = _win32_strdup_a,
-    .op_open           = _win32_open_a,
-    .op_create_temp    = _win32_create_temp_a,
-    .op_rename_temp    = _win32_rename_temp_a,
-    .op_remove         = _win32_remove_a
+    _win32_strdup_a,
+    _win32_open_a,
+    _win32_create_temp_a,
+    _win32_rename_temp_a,
+    _win32_remove_a
 };
 
 ZIP_EXTERN zip_source_t *

lib/zip_source_win32w.c

diff --git a/lib/zip_source_win32w.c b/lib/zip_source_win32w.c
index cf0801e..dd75cfb 100644
--- a/lib/zip_source_win32w.c
+++ b/lib/zip_source_win32w.c
@@ -44,11 +44,11 @@
 static int _win32_remove_w(const void *fname);
 
 static _zip_source_win32_file_ops_t win32_ops_w = {
-    .op_strdup       = _win32_strdup_w,
-    .op_open         = _win32_open_w,
-    .op_create_temp  = _win32_create_temp_w,
-    .op_rename_temp  = _win32_rename_temp_w,
-    .op_remove       = _win32_remove_w
+    _win32_strdup_w,
+    _win32_open_w,
+    _win32_create_temp_w,
+    _win32_rename_temp_w,
+    _win32_remove_w
 };
 
 ZIP_EXTERN zip_source_t *