package/coremark: Set cflags

The coremark build needs to set PORT_CFLAGS explicitly in order to pick
up the configured optmisation level, and other flags.

Signed-off-by: Joel Stanley <joel@jms.id.au>
Acked-by: Chris Packham <judge.packham@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
(cherry picked from commit c9a13ae0838174d1c05f026cee3ff66482620626)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/coremark/coremark.mk

@@ -11,6 +11,7 @@ COREMARK_LICENSE_FILES = LICENSE.md
 
 define COREMARK_BUILD_CMDS
 	$(TARGET_MAKE_ENV) $(MAKE) CC="$(TARGET_CC)" -C $(@D) \
+		PORT_CFLAGS="$(TARGET_CFLAGS)" \
 		PORT_DIR=linux$(if $(BR2_ARCH_IS_64),64) EXE= link
 endef