zdtm: shstk: add SHSTK_ENABLE test build option

* add SHSTK_ENABLE=1 toggle
* passes -mshstk to compiler and -z shstk to linker

Example:
  $ make -C test/zdtm/static clean
  $ make -C test/zdtm/static V=1 SHSTK_ENABLE=1 env00

  $ readelf --notes test/zdtm/static/env00 | grep SHSTK
      Properties: x86 feature: SHSTK

Signed-off-by: Igor Svilenkov Bozic <svilenkov@gmail.com>
Co-Authored-By: Andrei Vagin <avagin@gmail.com>

Author: 2 people

test/zdtm/Makefile.inc

@@ -66,6 +66,11 @@ endif
         export PKG_CONFIG_PATH
 endif
 
+ifeq ($(SHSTK_ENABLE),1)
+        CFLAGS  += -mshstk
+        LDFLAGS += -Wl,-z,shstk
+endif
+
 define pkg-libs
         $(shell PKG_CONFIG_PATH="$(PKG_CONFIG_PATH)" $(PKG_CONFIG) --libs $(1))
 endef
@@ -74,6 +79,7 @@ define pkg-cflags
         $(shell PKG_CONFIG_PATH="$(PKG_CONFIG_PATH)" $(PKG_CONFIG) --cflags $(1))
 endef
 
+
 %.d: %.c
 	$(E) " DEP      " $@
 	$(Q)$(CC) $(CFLAGS) $(CPPFLAGS) -MM -MP $< -o $@