package/lz4: only use PREFIX for host installation

As noted by Peter Korsgaard, using DESTDIR=$(HOST_DIR) and PREFIX=/usr
for the host installation is useless and actually incorrect (the
pkg-config file contains incorrect paths). Instead, using
PREFIX=$(HOST_DIR)/usr is simpler, and actually correct.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/lz4/lz4.mk

@@ -22,8 +22,8 @@ define HOST_LZ4_BUILD_CMDS
 endef
 
 define HOST_LZ4_INSTALL_CMDS
-	$(MAKE) $(HOST_CONFIGURE_OPTS) DESTDIR=$(HOST_DIR) \
-		PREFIX=/usr install -C $(@D)
+	$(MAKE) $(HOST_CONFIGURE_OPTS) PREFIX=$(HOST_DIR)/usr \
+		install -C $(@D)
 endef
 
 define LZ4_BUILD_CMDS