Remove a tab character from the definition of %__global_compiler_flags
    
    From https://bugzilla.redhat.com/2083296:
    
    > The issue is that some packages break up the flags at spaces,
    > in order to look for specific flags or to add flags of their own.
    >  The z3 package, for example, has some python code that does this:
    >
    >     def exec_cmd(cmd):
    >         if isinstance(cmd, str):
    >             cmd = cmd.split(' ')
    >         ...
    >
    > The result is one of the commands in the list consists of a single tab character.
    >  When that is passed to the compiler, the compiler does not like it at all.