fix a few linux compilation warnings

core/src/fpdfdoc/doc_basic.cpp

Index: core/src/fpdfdoc/doc_basic.cpp
diff --git a/core/src/fpdfdoc/doc_basic.cpp b/core/src/fpdfdoc/doc_basic.cpp
index 459ae87a0a38f965c40b64c01bac816f98d48bd7..d34149ed72e6824a64654cea6220229ea4debd7e 100644
--- a/core/src/fpdfdoc/doc_basic.cpp
+++ b/core/src/fpdfdoc/doc_basic.cpp
@@ -250,6 +250,7 @@ CPDF_Array*	CPDF_NameTree::LookupNamedDest(CPDF_Document* pDoc, FX_BSTR sName)
     }
     return NULL;
 }
+#if _FXM_PLATFORM_  == _FXM_PLATFORM_APPLE_ ||  _FXM_PLATFORM_  == _FXM_PLATFORM_WINDOWS_
 static CFX_WideString ChangeSlashToPlatform(FX_LPCWSTR str)
 {
     CFX_WideString result;
@@ -269,6 +270,20 @@ static CFX_WideString ChangeSlashToPlatform(FX_LPCWSTR str)
     }
     return result;
 }
+static CFX_WideString ChangeSlashToPDF(FX_LPCWSTR str)
+{
+    CFX_WideString result;
+    while (*str) {
+        if (*str == '\\' || *str == ':') {
+            result += '/';
+        } else {
+            result += *str;
+        }
+        str++;
+    }
+    return result;
+}
+#endif
 static CFX_WideString FILESPEC_DecodeFileName(FX_WSTR filepath)
 {
     if (filepath.GetLength() <= 1) {
@@ -349,19 +364,6 @@ FX_BOOL CPDF_FileSpec::IsURL() const
     }
     return ((CPDF_Dictionary*)m_pObj)->GetString(FX_BSTRC("FS")) == FX_BSTRC("URL");
 }
-static CFX_WideString ChangeSlashToPDF(FX_LPCWSTR str)
-{
-    CFX_WideString result;
-    while (*str) {
-        if (*str == '\\' || *str == ':') {
-            result += '/';
-        } else {
-            result += *str;
-        }
-        str++;
-    }
-    return result;
-}
 CFX_WideString FILESPEC_EncodeFileName(FX_WSTR filepath)
 {
     if (filepath.GetLength() <= 1) {