Patch series proposed upstream:

  <https://sourceware.org/pipermail/libc-alpha/2021-June/127473.html>

Author: Florian Weimer <fweimer@redhat.com>
Date:   Wed Jun 9 14:12:46 2021 +0200

    Makerules: Remove lib-version, $(subdir-version)
    
    Also clarify that the “versioned” term refers to the soname, not the glibc
    version (which also ends up in the installed file name).
    
    I verified on x86_64-linux-gnu that “make install” produces the same
    files.

diff --git a/Makerules b/Makerules
index ca9885436e15784b..d3f29d0b8991efc7 100644
--- a/Makerules
+++ b/Makerules
@@ -982,22 +982,21 @@ install-lib.so := $(filter %.so,$(install-lib:%_pic.a=%.so))
 install-lib := $(filter-out %.so %_pic.a,$(install-lib))
 
 ifeq (yes,$(build-shared))
-# Find which .so's have versions.
+# Find which .so's have a version number in their soname.
 versioned := $(strip $(foreach so,$(install-lib.so),\
 			       $(patsubst %,$(so),$($(so)-version))))
 
 install-lib.so-versioned := $(filter $(versioned), $(install-lib.so))
 install-lib.so-unversioned := $(filter-out $(versioned), $(install-lib.so))
 
-# For versioned libraries, we install three files:
+# For libraries whose soname have version numbers, we install three files:
 #	$(inst_libdir)/libfoo.so	-- for linking, symlink or ld script
 #	$(inst_slibdir)/libfoo.so.NN	-- for loading by SONAME, symlink
 #	$(inst_slibdir)/libfoo-X.Y.Z.so -- the real shared object file
-lib-version := $(firstword $($(subdir)-version) $(version))
 install-lib-nosubdir: $(install-lib.so-unversioned:%=$(inst_slibdir)/%) \
 		      $(foreach L,$(install-lib.so-versioned),\
 				$(inst_libdir)/$L \
-				$(inst_slibdir)/$(L:.so=)-$(lib-version).so \
+				$(inst_slibdir)/$(L:.so=)-$(version).so \
 				$(inst_slibdir)/$L$($L-version))
 
 # Install all the unversioned shared libraries.
@@ -1125,7 +1124,6 @@ include $(o-iterator)
 
 generated += $(foreach o,$(versioned),$o$($o-version))
 
-ifeq (,$($(subdir)-version))
 define o-iterator-doit
 $(inst_slibdir)/$o$($o-version): $(inst_slibdir)/$(o:.so=)-$(version).so \
 				 $(+force);
@@ -1140,23 +1138,7 @@ $(inst_slibdir)/$(o:.so=)-$(version).so: $(objpfx)$o $(+force);
 endef
 object-suffixes-left := $(versioned)
 include $(o-iterator)
-else
-define o-iterator-doit
-$(inst_slibdir)/$o$($o-version): \
-  $(inst_slibdir)/$(o:.so=)-$($(subdir)-version).so $(+force);
-	$$(make-shlib-link)
-endef
-object-suffixes-left := $(versioned)
-include $(o-iterator)
-
-define o-iterator-doit
-$(inst_slibdir)/$(o:.so=)-$($(subdir)-version).so: $(objpfx)$o $(+force);
-	$$(do-install-program)
-endef
-object-suffixes-left := $(versioned)
-include $(o-iterator)
-endif
-endif
+endif # ifneq (,$(versioned))
 
 define do-install-so
 $(do-install-program)