Alternate workaround for VS 2015 Update 2 code-gen bug

third_party/libxml/src/xmlstring.c

Index: third_party/libxml/src/xmlstring.c
diff --git a/third_party/libxml/src/xmlstring.c b/third_party/libxml/src/xmlstring.c
index d9b5085db430e7ce6b260f885472bccdf92017b6..b6dd10121845c39d114ada3af3b61ea8f5a6b134 100644
--- a/third_party/libxml/src/xmlstring.c
+++ b/third_party/libxml/src/xmlstring.c
@@ -821,13 +821,6 @@ xmlCheckUTF8(const unsigned char *utf)
  * the first 'len' characters of ARRAY
  */
 
-#if _MSC_FULL_VER && _MSC_FULL_VER == 190023918
-// Workaround for a /O1 ("s") optimization bug in VS 2015 Update 2, remove once
-// the fix is released. crbug.com/599427
-// https://connect.microsoft.com/VisualStudio/feedback/details/2582138
-#pragma optimize("t", on)
-#endif
-
 int
 xmlUTF8Strsize(const xmlChar *utf, int len) {
     const xmlChar   *ptr=utf;
@@ -842,20 +835,20 @@ xmlUTF8Strsize(const xmlChar *utf, int len) {
     while ( len-- > 0) {
         if ( !*ptr )
             break;
-        if ( (ch = *ptr++) & 0x80)
-            while ((ch<<=1) & 0x80 ) {
+        if ( (ch = *ptr++) & 0x80) {
+            // Workaround for an optimization bug in VS 2015 Update 2, remove
+            // once the fix is released. crbug.com/599427
+            // https://connect.microsoft.com/VisualStudio/feedback/details/2582138
+            xmlChar ch2 = ch;
+            while ((ch2<<=1) & 0x80 ) {
                 ptr++;
-		if (*ptr == 0) break;
-	    }
+                if (*ptr == 0) break;
+            }
+        }
     }
     return (ptr - utf);
 }
 
-#if _MSC_FULL_VER && _MSC_FULL_VER == 190023918
-// Restore the original optimization settings.
-#pragma optimize("", on)
-#endif
-
 /**
  * xmlUTF8Strndup:
  * @utf:  the input UTF8 *