apps/builtin/exec_builtin.c: Try posix_spawn if builtin apps do not have have an entry point.
apps/Application.mk: introduce MODULE config to simplify tristate(m)
apps/nsh: Change the nuttx shell module type to tristate
apps: Add loadable application support
script/mksymtab: Generate symbol table name by default
apps/builtin: Allow loadable applications can register with apps/builtin.
apps/examples/i2sloop: Add i2sloop application
This application can be used to test I2S loopback
nsh> i2sloop &
Signed-off-by: Masayuki Ishikawa <Masayuki.Ishikawa@jp.sony.com>
Approved-by: Gregory Nutt <gnutt@nuttx.org>