Allow re-targeting of naclports install

libraries/freetype-2.1.10/nacl-freetype-2.1.10.sh

Index: libraries/freetype-2.1.10/nacl-freetype-2.1.10.sh
diff --git a/libraries/freetype-2.1.10/nacl-freetype-2.1.10.sh b/libraries/freetype-2.1.10/nacl-freetype-2.1.10.sh
index 23509413bcf7c0eac6aed034512864ad2c2c1b4f..263748f95fa2eb570a8fcd5d78da6256b59a084b 100755
--- a/libraries/freetype-2.1.10/nacl-freetype-2.1.10.sh
+++ b/libraries/freetype-2.1.10/nacl-freetype-2.1.10.sh
@@ -22,9 +22,9 @@ CustomInstallStep() {
   # do the regular make install
   make install
   # move freetype up a directory so #include <freetype/freetype.h> works...
-  Remove ${NACL_SDK_USR_INCLUDE}/freetype
-  cp -R ${NACL_SDK_USR_INCLUDE}/freetype2/freetype ${NACL_SDK_USR_INCLUDE}/.
-  Remove ${NACL_SDK_USR_INCLUDE}/freetype2
+  Remove ${NACLPORTS_INCLUDE}/freetype
+  cp -R ${NACLPORTS_INCLUDE}/freetype2/freetype ${NACLPORTS_INCLUDE}/.
+  Remove ${NACLPORTS_INCLUDE}/freetype2
   DefaultTouchStep
 }