Mostly revert "build: add support for fixing up library soname"

This reverts commit b12288fa69.
The patchelf approach is too fragile, and the only users of this have been
converted to make patching unnecessary
Leave the abi_version_str variable in place in rules.mk

Signed-off-by: Felix Fietkau <nbd@nbd.name>

include/package-ipkg.mk

@@ -152,7 +152,6 @@ ifeq ($(DUMP),)
 	mkdir -p $(PKG_BUILD_DIR)/.pkgdir/$(1)
 	$(call Package/$(1)/install,$(PKG_BUILD_DIR)/.pkgdir/$(1))
 	$(call Package/$(1)/install_lib,$(PKG_BUILD_DIR)/.pkgdir/$(1))
-	$(if $(PKG_ABI_VERSION),$(SET_ABI_VERSION) "$(PKG_ABI_VERSION)" "$(PKG_BUILD_DIR)/.pkgdir/$(1)" "$(STAGING_DIR)/packages/$(STAGING_FILES_LIST)")
 	touch $$@
 
     $(STAGING_DIR_ROOT)/stamp/.$(1)_installed: $(PKG_BUILD_DIR)/.pkgdir/$(1).installed
@@ -197,15 +196,11 @@ $(_endef)
     $$(IPKG_$(1)) : export DESCRIPTION=$$(Package/$(1)/description)
     $$(IPKG_$(1)) : export PATH=$$(TARGET_PATH_PKG)
     $$(IPKG_$(1)) : export PKG_SOURCE_DATE_EPOCH:=$(PKG_SOURCE_DATE_EPOCH)
-    ifdef Build/InstallDev
-      $$(IPKG_$(1)): $(STAMP_INSTALLED)
-    endif
     $(PKG_INFO_DIR)/$(1).provides $$(IPKG_$(1)): $(STAMP_BUILT) $(INCLUDE_DIR)/package-ipkg.mk
 	@rm -rf $$(IDIR_$(1)); \
 		$$(call remove_ipkg_files,$(1),$$(call opkg_package_files,$(call gen_ipkg_wildcard,$(1))))
 	mkdir -p $(PACKAGE_DIR) $$(IDIR_$(1))/CONTROL $(PKG_INFO_DIR)
 	$(call Package/$(1)/install,$$(IDIR_$(1)))
-	$(if $(PKG_ABI_VERSION),$(SET_ABI_VERSION) "$(PKG_ABI_VERSION)" "$$(IDIR_$(1))" "$(STAGING_DIR)/packages/$(STAGING_FILES_LIST)")
 	$(if $(Package/$(1)/install-overlay),mkdir -p $(PACKAGE_DIR) $$(IDIR_$(1))/rootfs-overlay)
 	$(call Package/$(1)/install-overlay,$$(IDIR_$(1))/rootfs-overlay)
 	-find $$(IDIR_$(1)) -name 'CVS' -o -name '.svn' -o -name '.#*' -o -name '*~'| $(XARGS) rm -rf