kernel-doc: don't mangle whitespace in Example section

A section with the name "Example" (case-insensitive) has a special meaning
to kernel-doc.  These sections are output using mono-type fonts.  However,
leading whitespace is stripped, thus robbing a lot of meaning from this,
as indented code examples will be mangled.

This patch preserves the leading whitespace for "Example" sections.  More
accurately, it preserves it for all sections, but removes it later if the
section isn't an "Example" section.

Signed-off-by: Daniel Santos <daniel.santos@pobox.com>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Cc: Michal Marek <mmarek@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>