mksysmap: Add h8300 local symbol pattern

h8300's nm output have a lot of local symbols.
ex)
00000000 N .Lframe0
00000013 N .LLST1
00000026 N .LLST2
00000039 N .LLST3
0000004c N .LLST4
Added new pattern " .L" to filter rule.

Signed-off-by: Yoshinori Sato <ysato@users.sourceforge.jp>