Revert "use versioned libraries from now on for all architectures"

This reverts commit ecb02803c8.
It turned out that we run into unnecessary dynalic link problems when
minor (but compatible) changes cause *_MAINENANCE_VERSION to be
incremented even though the library is compatible.
Maybe use -soname MAJOR.MINOR or -soname MAJOR instead later?

configure/os/CONFIG_SITE.Common.linuxCommon

@@ -21,3 +21,9 @@ TARGET_LDFLAGS  += $(SYSROOT:%=--sysroot=%)
 ifeq ($(filter SL% RHEL%,$(T_A)),)
 VALID_BUILDS = Ioc Command
 endif
+
+# backward compatibility: Keep unversioned libs for older linux versions
+ifneq ($(filter SL% RHEL7% RHEL8%,$(T_A)),)
+SHRLIB_SUFFIX = $(SHRLIB_SUFFIX_BASE)
+LOADABLE_SHRLIB_SUFFIX = $(SHRLIB_SUFFIX_BASE)
+endif