arm: enable cpu cortex_a15 compiler flag

To enable the usage of virtualization extension related instructions
there is the need to enable the '-mcpu=cortex_a15' compiler flag on
those cpus. To not conflict with other compiler flags (Ref #810) we've
to disable the '-march=arm_v7a' flag.

Ref #1405

repos/base/mk/spec-arm_v7a.mk

@@ -7,9 +7,6 @@
 # denote wich specs are also fullfilled by this spec
 SPECS += arm_v7
 
-# configure compiler
-CC_MARCH += -march=armv7-a
-
 # add repository relative include paths
 REP_INC_DIR += include/arm_v7a
 

repos/base/mk/spec-cortex_a15.mk

@@ -10,18 +10,17 @@ SPECS += arm_v7a
 # add repository relative include paths
 REP_INC_DIR += include/cortex_a15
 
+# configure compiler
 #
 # GCC versions up to 4.7.3 complain about conflicting command-line switches:
 #
 #   warning: switch -mcpu=cortex-a15 conflicts with -march=armv7-a switch [enabled by default]
 #
-# Therefore, do not specify the actual CPU and stay with just the architecture
-# for now.
+# Therefore, do not specify the actual CPU and the architecture together.
 #
 # Reference: https://github.com/genodelabs/genode/issues/810
 #
-#CC_OPT += -mcpu=cortex-a15
+CC_MARCH += -mcpu=cortex-a15
 
 # include implied specs
 include $(call select_from_repositories,mk/spec-arm_v7a.mk)
-

repos/base/mk/spec-cortex_a8.mk

@@ -10,7 +10,8 @@ SPECS += arm_v7a
 # add repository relative include paths
 REP_INC_DIR += include/cortex_a8
 
-CC_OPT += -mcpu=cortex-a8
+# configure compiler
+CC_MARCH += -march=armv7-a -mcpu=cortex-a8
 
 # include implied specs
 include $(call select_from_repositories,mk/spec-arm_v7a.mk)

repos/base/mk/spec-cortex_a9.mk

@@ -10,7 +10,8 @@ SPECS += arm_v7a pl390
 # add repository relative include paths
 REP_INC_DIR += include/cortex_a9
 
-CC_OPT += -mcpu=cortex-a9
+# configure compiler
+CC_MARCH += -march=armv7-a -mcpu=cortex-a9
 
 # include implied specs
 include $(call select_from_repositories,mk/spec-arm_v7a.mk)

repos/dde_rump/lib/mk/rump_base.inc

@@ -35,7 +35,7 @@ BUILD_CMD = BUILD_CC=cc BUILD_AR=ar BUILD_NM=nm BUILD_OBJCOPY=objcopy \
 # Linkage
 #
 ARCHIVE = $(RUMP_LIB)/librump.a
-CC_OPT  = -DLIBRUMPUSER
+CC_OPT += -DLIBRUMPUSER
 
 
 INCSDIRS = adosfs altq arpa crypto dev evbarm filecorefs fs i386 isofs miscfs \