Fix a typo with PAGEMODE_UNKNOWN.

fpdfsdk/src/fpdf_ext.cpp

Index: fpdfsdk/src/fpdf_ext.cpp
diff --git a/fpdfsdk/src/fpdf_ext.cpp b/fpdfsdk/src/fpdf_ext.cpp
index 2d9e5ae74cc9b966d3283b7ae9372e3d6053d09d..916cb2069cdd11bdbe5c5d9de8e59668bec1e9cc 100644
--- a/fpdfsdk/src/fpdf_ext.cpp
+++ b/fpdfsdk/src/fpdf_ext.cpp
@@ -219,10 +219,10 @@ void CheckUnSupportError(CPDF_Document * pDoc, FX_DWORD err_code)
 
 DLLEXPORT int FPDFDoc_GetPageMode(FPDF_DOCUMENT document)
 {
-	if (!document) return PAGEMODE_UNKONOWN;
+	if (!document) return PAGEMODE_UNKNOWN;
 	CPDF_Dictionary *pRoot = ((CPDF_Document*)document)->GetRoot();
 	if (!pRoot)
-		return PAGEMODE_UNKONOWN;
+		return PAGEMODE_UNKNOWN;
 	CPDF_Object* pName = pRoot->GetElement("PageMode");
 	if (!pName)
 		return PAGEMODE_USENONE;
@@ -241,5 +241,5 @@ DLLEXPORT int FPDFDoc_GetPageMode(FPDF_DOCUMENT document)
 	else if (strPageMode.EqualNoCase(FX_BSTR("UseAttachments")))
 		return PAGEMODE_USEATTACHMENTS;
 
-	return PAGEMODE_UNKONOWN;
+	return PAGEMODE_UNKNOWN;
 }