ffmpeg: fix style concerns for Solaris section

Signed-off-by: Rafaël Carré <funman@videolan.org>
(cherry picked from commit ffabc04f18611f362390b5acc95ee8a4bdcb3c23)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

contrib/src/ffmpeg/rules.mak

@@ -135,6 +135,7 @@ else # !Windows
 FFMPEGCONF += --enable-pthreads
 endif
 
+# Solaris
 ifdef HAVE_SOLARIS
 ifeq ($(ARCH),x86_64)
 FFMPEGCONF += --cpu=core2