mk: force --no-as-needed for spdk libs.

When building shared libs, we specifically don't set the --as-needed
flag so that we still link against libraries that have constructor
functions. LD reports on its man page that the default behavior is
equivalent to --no-as-needed.

For RHEL based distros like fedora and centos this works fine. While
the LD man page shipped with ubuntu distributions also states that
--no-as-needed is the default, they don't respect that behavior and do
--as-needed linking unless you force them with --no-as-needed.

Signed-off-by: Seth Howell <seth.howell@intel.com>
Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/464621 (master)

(cherry picked from commit e29c6fe133)
Change-Id: I914ab849323de198af5c5e53fffb1f57fcaff5fe
Signed-off-by: Seth Howell <seth.howell@intel.com>
Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/467292
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>

lib/env_dpdk/env.mk

@@ -116,7 +116,7 @@ ENV_CFLAGS = $(DPDK_INC) -Wno-deprecated-declarations
 ENV_CXXFLAGS = $(ENV_CFLAGS)
 ENV_DPDK_FILE = $(call spdk_lib_list_to_static_libs,env_dpdk)
 ENV_LIBS = $(ENV_DPDK_FILE) $(DPDK_LIB)
-ENV_LINKER_ARGS = $(ENV_DPDK_FILE) -Wl,--whole-archive $(DPDK_LIB) -Wl,--no-whole-archive
+ENV_LINKER_ARGS = $(ENV_DPDK_FILE) -Wl,--whole-archive,--no-as-needed $(DPDK_LIB) -Wl,--no-whole-archive
 
 ifeq ($(CONFIG_IPSEC_MB),y)
 ENV_LINKER_ARGS += -lIPSec_MB -L$(IPSEC_MB_DIR)

mk/spdk.app_vars.mk

@@ -35,6 +35,7 @@ SPDK_LIB_FILES = $(call spdk_lib_list_to_static_libs,$(SPDK_LIB_LIST))
 SPDK_LIB_LINKER_ARGS = \
 	-L$(SPDK_ROOT_DIR)/build/lib \
 	-Wl,--whole-archive \
+	-Wl,--no-as-needed \
 	$(SPDK_LIB_LIST:%=-lspdk_%) \
 	-Wl,--no-whole-archive