configure: Added --disable-apps option.

Together with options to disable examples, tests and unit-tests
this will enable us to build SPDK without linking any executables.

This is useful for packaging SPDK in applications - especially
those using own ENV.

Fixes #1877

Signed-off-by: Rajarshi Chowdhury <rajarshi.chowdhury@oracle.com>
Change-Id: I0467ec497d2abe2fad40cdb4ba723a240bee46d6
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/7462
Community-CI: Broadcom CI
Community-CI: Mellanox Build Bot
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
Reviewed-by: Aleksey Marchuk <alexeymar@mellanox.com>

CONFIG

@@ -76,6 +76,9 @@ CONFIG_UNIT_TESTS=y
 # Build examples
 CONFIG_EXAMPLES=y
 
+# Build apps
+CONFIG_APPS=y
+
 # Build with Control-flow Enforcement Technology (CET)
 CONFIG_CET=n
 

Makefile

@@ -40,8 +40,9 @@ include $(SPDK_ROOT_DIR)/mk/spdk.common.mk
 DIRS-y += lib
 DIRS-y += module
 DIRS-$(CONFIG_SHARED) += shared_lib
-DIRS-y += app include
+DIRS-y += include
 DIRS-$(CONFIG_EXAMPLES) += examples
+DIRS-$(CONFIG_APPS) += app
 DIRS-y += test
 DIRS-$(CONFIG_IPSEC_MB) += ipsecbuild
 DIRS-$(CONFIG_ISAL) += isalbuild

configure

@@ -35,6 +35,7 @@ function usage() {
 	echo " --disable-tests           Disable building of functional tests"
 	echo " --disable-unit-tests      Disable building of unit tests"
 	echo " --disable-examples        Disable building of examples"
+	echo " --disable-apps            Disable building of apps"
 	echo ""
 	echo "Specifying Dependencies:"
 	echo "--with-DEPENDENCY[=path]   Use the given dependency. Optionally, provide the"
@@ -265,6 +266,12 @@ for i in "$@"; do
 		--disable-examples)
 			CONFIG[EXAMPLES]=n
 			;;
+		--enable-apps)
+			CONFIG[APPS]=y
+			;;
+		--disable-apps)
+			CONFIG[APPS]=N
+			;;
 		--enable-werror)
 			CONFIG[WERROR]=y
 			;;