misleading #line directive error message fix

All the reasons of commit are described in a bug report in bugzilla there https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105005 .

results of edge case testing with adequate console output after "gcc -E example.c -o example" command: 1)

1 #line
2 #warning "some warning, not an EOF"

example.c:1:6: error: missing #line directive arguments
    1 | #line
      |      ^
example.c:2:2: warning: #warning "some warning, not an EOF" [-Wcpp]
    2 | #warning "some warning, not an EOF"
      |  ^~~~~~~

1 #line
2  

example.c:1:6: error: missing #line directive arguments
    1 | #line
      |      ^

1 #line

example.c:1:6: error: unexpected end of file after #line
    1 | #line
      |      ^