Fix duplicate spotless target in com32/libutil/Makefile.

Signed-off-by: Gene Cumm <gene.cumm@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

"make clean" must NOT remove stuff that "make installer" should not
rebuild.  This is a somewhat unfortunate choice of naming, but that's
the way it is.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Cleanup and centralize the Makefile system even more.
Fix a gcc 4.3 incompatibility in memdisk (definition of strlen).

Compile with -std=gnu99, this allows us to define initializers inside
for() loops, which makes certain kinds of ugly macros easier to write.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Begin the process of centralizing configurables.

Improve "make install" and "make netinstall"; add "make
extbootinstall".

Move source files out of the root directory; the root is a mess and
has become virtually unmaintainable.  The Syslinux core now lives in
core/; the Linux and generic utilities has moved into utils/, and
copybs.com has moved into dos/; it had to go somewhere, and it seemed
as good a place as any.

Use $(CC) in gcc_ok macro, not plain gcc.  This seems to work, iff the
gcc_ok macro is declared with =, not :=

Use "-nostdinc -iwithprefix include" to prevent the inclusion of
system header files, but still permitting *compiler* header files.