Fixup incorrect include guards.

xfa/src/fgas/include/fx_alg.h

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
-#ifndef _FX_ALGORITHM
-#define _FX_ALGORITHM
+#ifndef XFA_SRC_FGAS_INCLUDE_FX_ALG_H_
+#define XFA_SRC_FGAS_INCLUDE_FX_ALG_H_
+
 #define FX_IsOdd(a) ((a)&1)
 #ifdef __cplusplus
 extern "C" {
 #endif
 int32_t FX_Base64EncodeA(const uint8_t* pSrc, int32_t iSrcLen, FX_CHAR* pDst);
 int32_t FX_Base64DecodeA(const FX_CHAR* pSrc, int32_t iSrcLen, uint8_t* pDst);
 int32_t FX_Base64DecodeW(const FX_WCHAR* pSrc, int32_t iSrcLen, uint8_t* pDst);
 uint8_t FX_Hex2Dec(uint8_t hexHigh, uint8_t hexLow);
 int32_t FX_SeparateStringW(const FX_WCHAR* pStr,
                            int32_t iStrLen,
@@ skipping 18 matching lines @@
         return iMid;
       } else if (find < v) {
         iEnd = iMid - 1;
       } else {
         iStart = iMid + 1;
       }
     } while (iStart <= iEnd);
     return -1;
   }
 };
-#endif
+
+#endif  // XFA_SRC_FGAS_INCLUDE_FX_ALG_H_