package/dash: fix static with shared build

When BR2_SHARED_STATIC_LIBS is enabled we pass both --enable-static and
--enable-shared to configure. dash configure.ac only looks for
--enable-static to make the build static. But when linking against
libedit pkg-config only returns dynamic linking dependencies, so the
indirect ncurses dependency in not mentioned. The end result is that
libedit can't find ncurses symbols on link.

BR2_SHARED_STATIC_LIBS only makes sense for libraries, not executable
binaries. Pass --disable-static unless BR2_STATIC_LIBS is enabled for
static only build.

Fixes:
http://autobuild.buildroot.net/results/137d39cc5ec436759a2fde3f26ce5633e0ad6c2e/
http://autobuild.buildroot.net/results/55a38e0e45212bf7403d9ccb626c9422e3affe72/
http://autobuild.buildroot.net/results/8f109f1a04a6a2ff6d8c4c920e499fbaec3f72b9/



Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>