A relative jump of +1 is the same than 0, we need +2 to skip the next
instruction.
Use named label so it is more clear than +2.

Read the InstallDir regkey, "" points to vlc.exe
(cherry picked from commit b0c000c5883225d0edb4f268d967c77d07254dce)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>