[build] option to disable executable build (#3391)

examples/apps/Makefile.am

@@ -40,6 +40,7 @@ DIST_SUBDIRS                            = \
 SUBDIRS                                 = \
     $(NULL)
 
+if OPENTHREAD_ENABLE_EXECUTABLE
 if OPENTHREAD_ENABLE_CLI
 SUBDIRS                                += cli
 endif
@@ -47,6 +48,7 @@ endif
 if OPENTHREAD_ENABLE_NCP
 SUBDIRS                                += ncp
 endif
+endif
 
 # Always pretty (e.g. for 'make pretty') these subdirectories.
 

examples/common-switches.mk

@@ -131,6 +131,10 @@ ifeq ($(DISABLE_BUILTIN_MBEDTLS), 1)
 configure_OPTIONS              += --disable-builtin-mbedtls
 endif
 
+ifeq ($(DISABLE_EXECUTABLE), 1)
+configure_OPTIONS              += --enable-executable=no
+endif
+
 ifeq ($(DEBUG_UART),1)
 CFLAGS   += -DOPENTHREAD_CONFIG_ENABLE_DEBUG_UART=1
 CXXFLAGS += -DOPENTHREAD_CONFIG_ENABLE_DEBUG_UART=1