Incorrect handling of logical condition in preprocessing

Jom version: 1.1.3 (the latest available from https://wiki.qt.io/Jom)

The following makefile errors out, because preprocessor condition is wrongly evaluated to true:

    !if !defined(PATH) && !defined(TEMP)
    !error PATH and TEMP not defined
    !endif

nmake reports no error for this makefile.

A check similar to the above prevents building Tcl/Tk with Jom.