style: Use clang-format as formatter and linter tool

We want to keep the code style consistent, this first commit adds a
.clang-format in order to "document" our style code.

This patch also adds a target *linter* to Makefile which will complain
if we have any style issue on test and src dirs.

I have run the follow command to create the .clang-format file:

        $ clang-format -style=mozilla -dump-config > .clang-format

And I also made some adjusts to .clang-format changing the following
properties:

        PointerAlignment: Right
        ColumnLimit:     120

Commands executed to fix the current styling:

        $ find . -name *.h | xargs clang-format -i
        $ find . -name *.c | xargs clang-format -i

Signed-off-by: Johnny Richard <johnny@johnnyrichard.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/test/munit.h b/test/munit.h
index 8460a45..c614c78 100644
--- a/test/munit.h
+++ b/test/munit.h
@@ -1,3 +1,4 @@
+// clang-format off
 /* µnit Testing Framework
  * Copyright (c) 2013-2017 Evan Nemerson <evan@nemerson.com>
  *