cmake: disable shared lib for maemo

Signed-off-by: Corentin Chary <corentin.chary@gmail.com>

# Please enter the commit message for your changes. Lines starting
# with '#' will be ignored, and an empty message aborts the commit.
# On branch master
# Changes to be committed:
#   (use "git reset HEAD <file>..." to unstage)
#
#	modified:   common/CMakeLists.txt
#	modified:   pkg/maemo5/debian/changelog
#	modified:   pkg/maemo5/debian/install
#
# Untracked files:
#   (use "git add <file>..." to include in what will be committed)
#
#	debian
#	pkg/maemo5/debian/lugdulov.stubvars
#	pkg/maemo5/debian/substvars
