Made the following change to both of the aforementioned files in order to get SpellCheckerPlugin.cpp to compile.
diff --git a/src/plugins/contrib/SpellChecker/SpellChecker_wx31_64.cbp b/src/plugins/contrib/SpellChecker/SpellChecker_wx31_64.cbp
--- a/src/plugins/contrib/SpellChecker/SpellChecker_wx31_64.cbp
+++ b/src/plugins/contrib/SpellChecker/SpellChecker_wx31_64.cbp
@@ -74,7 +74,7 @@
                <Add option="-Winvalid-pch" />
                <Add option="-DCB_PRECOMP" />
                <Add option="-DcbDEBUG" />
-               <Add directory="hunspell/src" />
+               <Add directory="hunspell/src/hunspell" />
                <Add directory="wxspellchecker/include" />
                <Add directory="../../../include" />
                <Add directory="../../../include/tinyxml" />
diff --git a/src/plugins/contrib/SpellChecker/SpellChecker_wx32_64.cbp b/src/plugins/contrib/SpellChecker/SpellChecker_wx32_64.cbp
--- a/src/plugins/contrib/SpellChecker/SpellChecker_wx32_64.cbp
+++ b/src/plugins/contrib/SpellChecker/SpellChecker_wx32_64.cbp
@@ -74,7 +74,7 @@
                <Add option="-Winvalid-pch" />
                <Add option="-DCB_PRECOMP" />
                <Add option="-DcbDEBUG" />
-               <Add directory="hunspell/src" />
+               <Add directory="hunspell/src/hunspell" />
                <Add directory="wxspellchecker/include" />
                <Add directory="../../../include" />
                <Add directory="../../../include/tinyxml" />
Otherwise it couldn't find hunspell.h
Is anyone else having this problem?