fix typo which caused blank version when compiling without the build script

This was introduced in e8880cb6d7ac0853b5f2ac9c840fea8392a73bef
sync the PDF API header

This was edited directly in 51036e686401251dbf550b3f884fb2f02d84c8d1 and would
have been lost when the headers were resynced
support building with non-patched QT5

This was tested only with QT 5.0 and no validation was done whether
it compiles or works properly with QT4.