Build warning about duplicate definition of NOTHING

[Hans-Bernhard Bröker]

Dear nano developers,

a build from a tarball made from current git sources would now trigger a 
macro redefinition warning because of this change to src/definitions.h 
by commit 3ea2694d9c0f590fda7973d519936b0578eac449:

-#define CNONE           (1<<1)
+#define NOTHING      (1<<1)

This definition of "NOTHING" collides with the one in generated file 
"revision.h" in case the configury did not detect a build from git:

#define NOTHING "from tarball"

Generally speaking I would advise against defining globally visible 
enums as macros, and against doing either without any kind of name-space 
prefix.

As an aside, I only noticed this because the detection logic for a build 
from git fails in an out-of-tree build.  It checks for the presence of a 
file in the build root which only exists in the source root.  This 
should help:

diff --git a/configure.ac b/configure.ac
index 4d2a5c19..09c6d0c0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -59,7 +59,7 @@ AC_DEFINE_DIR([PKGDATADIR], [pkgdatadir], [Where data 
are placed to.])
 dnl Whether this is a git repository.

 AC_MSG_CHECKING([whether building from git])
-if test -f roll-a-release.sh ; then
+if test -f $srcdir/roll-a-release.sh ; then
        AC_MSG_RESULT([yes])
        from_git=yes
 else


Hope this helps

Hans-Bernhard