bug#23771: Eliminating compiler warnings

[Ken Brown]

I would like to get rid of all compiler warnings in the Cygwin builds 
(X11, w32, and nox).  There are currently none in the X11 build, but 
there are a lot in the other builds.  Many of the warnings in the w32 
build probably occur in the MinGW build also.  And all of the warnings 
in the nox build would occur in any build without a window system.

The seven patches attached attempt to eliminate all the currently 
existing warnings.  There is one patch for each type of warning.  Since 
they affect other platforms besides Cygwin, I won't install them until 
someone has had a chance to review them.  There's obviously no rush 
about this.

Two comments: First, patch 0006-... is there because there might be a 
jump over an AUTO_STRING call.  (This happens exactly once in the 
Cygwin-w32 build.)  It seems stupid to have to worry about this.  An 
alternative would be to just disable the -Wjump-misses-init warning.

Second, patch 0007-... is there because I couldn't think of a reasonable 
way to avoid -Waddress warnings when compiling w32fns.c, w32menu.c, and 
menu.c in the Cygwin-w32 build.  Everything I thought of would have made 
the code very ugly.  So I simply disabled that warning for the 
Cygwin-w32 build, and I took the liberty of doing the same thing for the 
MinGW build, which I think is also affected in some cases.  If someone 
sees a better way of eliminating those warnings, that would be preferable.

Ken

0001-Eliminate-noreturn-warnings-if-there-s-no-window-sys.patch
Description: Text document

0002-Fix-unused-variable-compiler-warnings.patch
Description: Text document

0003-Avoid-empty-body-compiler-warnings.patch
Description: Text document

0004-Fix-format-compiler-warnings.patch
Description: Text document

0005-Don-t-define-unneeded-function-on-Cygwin.patch
Description: Text document

0006-Avoid-jump-misses-init-compiler-warnings.patch
Description: Text document

0007-Avoid-address-compiler-warnings.patch
Description: Text document