Hi,

Here's a proposal for supporting Flymake in C/C++. This patch:

- Sets up Flymake in c-mode buffers (heads up Alan), but doesn't
  automatically enable it.

- Adds a special target to src/Makefile so that Flymake can work with
  Emacs's C sources (using a default cc-flymake-use-special-make-target
  method).

- The special target's name is 'check-syntax' and uses CHK_SOURCES,
  which lets older Emacsen edit new Emacs sources with old Flymake
  implementations (dubious but harmless advantage).

- Is customizable by the user to use a zero-configuration method that
  guesses GCC flags from Makefiles (see
  cc-flymake-use-cc-directly). This probably works in the simplest
  scenarios(*)

- Is programmable by the user to use any other self-configuration
  technique (this includes per-file/dir manual configuration using a
  file-local cc-flymake-command)

*: Sadly, GNU Hello no longer works since it uses a backquoted shell
  expression that the current implementation can't intercept (my old
  use-emacs-as-a-shell-parser )
  Here it is, for reference

gcc -DLOCALEDIR=\"/usr/local/share/locale\" -DHAVE_CONFIG_H -I. -I. -I.. -I. -I. -I.. -I../intl -I../intl    -g -O2 -c `test -f 'hello.c' || echo './'`hello.c

Also, FTR, discovered that -M flags do not seem to harm syntax-checking.
No idea if dependencies files are still created anyway though.

João