[source] build: fix regression in handling ABI_VERSION

[LEDE Commits]

nbd pushed a commit to source.git, branch master:
https://git.lede-project.org/f784b3e195cf5932347f0c2297b8604da93d12e3

commit f784b3e195cf5932347f0c2297b8604da93d12e3
Author: Felix Fietkau <nbd at nbd.name>
AuthorDate: Sat Jan 21 18:29:56 2017 +0100

    build: fix regression in handling ABI_VERSION
    
    The code was updated without changing $$@ into the proper target
    filename
    
    Signed-off-by: Felix Fietkau <nbd at nbd.name>
---
 include/package-ipkg.mk | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/package-ipkg.mk b/include/package-ipkg.mk
index d73d461..3e2e31c 100644
--- a/include/package-ipkg.mk
+++ b/include/package-ipkg.mk
@@ -148,7 +148,7 @@ ifeq ($(DUMP),)
 
     $(STAGING_DIR_ROOT)/stamp/.$(1)_installed: $(PKG_BUILD_DIR)/.pkgdir/$(1).installed
 	mkdir -p $(STAGING_DIR_ROOT)/stamp
-	$(if $(ABI_VERSION),echo '$(ABI_VERSION)' | cmp -s - $$@ || echo '$(ABI_VERSION)' > $$@)
+	$(if $(ABI_VERSION),echo '$(ABI_VERSION)' | cmp -s - $(PKG_INFO_DIR)/$(1).version || echo '$(ABI_VERSION)' > $(PKG_INFO_DIR)/$(1).version)
 	$(call locked,$(CP) $(PKG_BUILD_DIR)/.pkgdir/$(1)/. $(STAGING_DIR_ROOT)/,root-copy)
 	touch $$@