compat/posix.h: clean up GIT_GNUC_PREREQ() and UNUSED

Fix the preprocessor indentation of the GIT_GNUC_PREREQ() and UNUSED
macros according to the CodingGuidelines, without changing their
behavior.

Adjust the spelling in the GIT_GNUC_PREREQ() comment block.

Signed-off-by: Dominik Loidolt <dominik.loidolt@univie.ac.at>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

compat/posix.h

diff --git a/compat/posix.h b/compat/posix.h
index 273cb87..d2de5ce 100644
--- a/compat/posix.h
+++ b/compat/posix.h
@@ -5,11 +5,10 @@
 
 /*
  * Derived from Linux "Features Test Macro" header
- * Convenience macros to test the versions of gcc (or
- * a compatible compiler).
+ * Convenience macros to test the versions of GCC (or a compatible compiler).
  * Use them like this:
  *  #if GIT_GNUC_PREREQ (2,8)
- *   ... code requiring gcc 2.8 or later ...
+ *   ... code requiring GCC 2.8 or later ...
  *  #endif
  *
  * Note that Clang and other compilers define __GNUC__ for compatibility; use
@@ -17,12 +16,12 @@
  *
  * This macro of course is not part of POSIX, but we need it for the UNUSED
  * macro which is used by some of our POSIX compatibility wrappers.
-*/
+ */
 #if defined(__GNUC__) && defined(__GNUC_MINOR__)
 # define GIT_GNUC_PREREQ(maj, min) \
 	((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min))
 #else
- #define GIT_GNUC_PREREQ(maj, min) 0
+# define GIT_GNUC_PREREQ(maj, min) 0
 #endif
 
 /* Similar for Clang. */
@@ -48,13 +47,13 @@
  * compilation, consider using MAYBE_UNUSED instead.
  */
 #if GIT_GNUC_PREREQ(4, 5) || GIT_CLANG_PREREQ(2, 9)
-#define UNUSED __attribute__((unused)) \
-	__attribute__((deprecated ("parameter declared as UNUSED")))
+# define UNUSED __attribute__((unused)) \
+	__attribute__((deprecated("parameter declared as UNUSED")))
 #elif defined(__GNUC__)
-#define UNUSED __attribute__((unused)) \
+# define UNUSED __attribute__((unused)) \
 	__attribute__((deprecated))
 #else
-#define UNUSED
+# define UNUSED
 #endif
 
 #ifdef __MINGW64__