treewide: revise library packaging

- Annotate versionless libraries (such as libubox, libuci etc.) with a fixed
  ABI_VERSION resembling the source date of the last incompatible change
- Annotate packages shipping versioned library objects with ABI_VERSION
- Stop shipping unversioned library symlinks for packages with ABI_VERSION

Ref: https://openwrt.org/docs/guide-developer/package-policies#shared_libraries
Ref: https://github.com/KanjiMonster/maintainer-tools/blob/master/check-abi-versions.pl
Signed-off-by: Jo-Philipp Wich <jo@mein.io>

package/libs/sysfsutils/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=sysfsutils
 PKG_VERSION:=2.1.0
-PKG_RELEASE:=2
+PKG_RELEASE:=3
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=@SF/linux-diag
@@ -31,6 +31,7 @@ define Package/libsysfs
   SUBMENU:=Filesystem
   TITLE:=Sysfs library
   URL:=http://linux-diag.sourceforge.net/Sysfsutils.html
+  ABI_VERSION:=2
 endef
 
 define Package/sysfsutils
@@ -61,7 +62,7 @@ endef
 
 define Package/libsysfs/install
 	$(INSTALL_DIR) $(1)/usr/lib
-	$(CP) $(PKG_INSTALL_DIR)/usr/lib/libsysfs.so* $(1)/usr/lib/
+	$(CP) $(PKG_INSTALL_DIR)/usr/lib/libsysfs.so.* $(1)/usr/lib/
 endef
 
 define Package/sysfsutils/install