build: limit usage of vpath

All paths are now explicitly given, and the object tree mimics
the source tree, so there is no need to apply special vpaths.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/Makefile.target b/Makefile.target
index 555894d..2907aad 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -8,12 +8,11 @@
 include $(HWDIR)/config.mak
 endif
 
-TARGET_PATH=$(SRC_PATH)/target-$(TARGET_BASE_ARCH)
-$(call set-vpath, $(SRC_PATH):$(TARGET_PATH):$(SRC_PATH)/hw)
+$(call set-vpath, $(SRC_PATH))
 ifdef CONFIG_LINUX
 QEMU_CFLAGS += -I../linux-headers
 endif
-QEMU_CFLAGS += -I.. -I$(TARGET_PATH) -DNEED_CPU_H
+QEMU_CFLAGS += -I.. -I$(SRC_PATH)/target-$(TARGET_BASE_ARCH) -DNEED_CPU_H
 
 QEMU_CFLAGS+=-I$(SRC_PATH)/include