Use backticks instead of non-portable make $(shell ...) function

The backticks are treated like text, until the shell expands them, thus
making this solution portable.

scripts/Makefile.am

@@ -172,7 +172,7 @@ check: $(TEST_FILES) $(wildcard $(srcdir)/t/200_Dpkg_Shlibs/ld.so.conf*) mkdir_t
 	cp -dRl $(srcdir)/t/200_Dpkg_Shlibs/ld.so.conf* t.tmp/
 	PATH="$(top_builddir)/src:$(top_builddir)/scripts:$(PATH)" srcdir=$(srcdir) PERL5LIB=$(srcdir) DPKG_DATADIR=$(srcdir)/.. PERL_DL_NONLAZY=1 $(PERL) -I$(srcdir) "-MExtUtils::Command::MM" "-e" "test_harness($(TEST_VERBOSE), '.')" $(TEST_FILES)
 
-objdump_lib_name = lib$(shell basename $@).so
+objdump_lib_name = lib`basename $@`.so
 $(srcdir)/t/200_Dpkg_Shlibs/objdump.tags-amd64 $(srcdir)/t/200_Dpkg_Shlibs/objdump.tags-i386: $(srcdir)/t/200_Dpkg_Shlibs/symboltags.c
 	$(CC) $(CFLAGS) -shared -fPIC -Wl,-soname -Wl,libsymboltags.so.1 $< \
 	  $(if $(findstring amd64,$@),-DAMD64,) -o $(objdump_lib_name)