tools headers: Synchronize linux/build_bug.h with the kernel sources

To pick up the changes in:

  6ffd853b0b ("build_bug.h: correct function parameters names in kernel-doc")

That just add some comments, addressing this perf tools build warning:

  Warning: Kernel ABI header differences:
    diff -u tools/include/linux/build_bug.h include/linux/build_bug.h

Please take a look at tools/include/uapi/README for further info on this
synchronization process.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/include/linux/build_bug.h

@@ -32,7 +32,8 @@
 /**
  * BUILD_BUG_ON_MSG - break compile if a condition is true & emit supplied
  *		      error message.
- * @condition: the condition which the compiler should know is false.
+ * @cond: the condition which the compiler should know is false.
+ * @msg: build-time error message
  *
  * See BUILD_BUG_ON for description.
  */
@@ -60,6 +61,7 @@
 
 /**
  * static_assert - check integer constant expression at build time
+ * @expr: expression to be checked
  *
  * static_assert() is a wrapper for the C11 _Static_assert, with a
  * little macro magic to make the message optional (defaulting to the