Fixed compilation errors with 'isascii' on some systems.

src/text.cpp

@@ -20,6 +20,7 @@
 #include "vmime/text.hpp"
 
 #include "vmime/utility/stringUtils.hpp"
+#include "vmime/parserHelpers.hpp"
 
 #include "vmime/encoder.hpp"
 #include "vmime/encoderB64.hpp"

src/utility/stringUtils.cpp

@@ -18,6 +18,7 @@
 //
 
 #include "vmime/utility/stringUtils.hpp"
+#include "vmime/parserHelpers.hpp"
 
 
 namespace vmime {