C warning in MSYS2 build

[Richard Copley]

Hi,

One more warning crept into the MSYS2 build after the recent update to
the system headers/libraries:

make[1]: Entering directory '/c/projects/emacs/src'
  CC       indent.o
indent.c: In function 'scan_for_column':
indent.c:69:10: warning: potential null pointer dereference [-Wnull-dereference]
   return 0;
          ^
indent.c:69:10: warning: potential null pointer dereference [-Wnull-dereference]
indent.c:69:10: warning: potential null pointer dereference [-Wnull-dereference]
indent.c:69:10: warning: potential null pointer dereference [-Wnull-dereference]
make[1]: Leaving directory '/c/projects/emacs/src'