filearch: Add s390 and s390x detection and tests.

Unfortunately I was unable to build s390 binaries since multilib was
dropped in Fedora 24 on s390x.  Going from the source of the 'file'
command it seems as if it prints "32-bit" (the architecture is really
31 bit).

test-data/Makefile.am

@@ -42,6 +42,7 @@ image_files = \
 	$(srcdir)/binaries/bin-ppc64-dynamic \
 	$(srcdir)/binaries/bin-ppc64le-dynamic \
 	$(srcdir)/binaries/bin-riscv64-dynamic \
+	$(srcdir)/binaries/bin-s390x-dynamic \
 	$(srcdir)/binaries/bin-sparc-dynamic \
 	$(srcdir)/binaries/bin-win32.exe \
 	$(srcdir)/binaries/bin-win64.exe \
@@ -54,6 +55,7 @@ image_files = \
 	$(srcdir)/binaries/lib-ppc64.so \
 	$(srcdir)/binaries/lib-ppc64le.so \
 	$(srcdir)/binaries/lib-riscv64.so \
+	$(srcdir)/binaries/lib-s390x.so \
 	$(srcdir)/binaries/lib-sparc.so \
 	$(srcdir)/binaries/lib-win32.dll \
 	$(srcdir)/binaries/lib-win64.dll \

test-data/binaries/Makefile.am

@@ -27,6 +27,7 @@ EXTRA_DIST = \
 	bin-ppc64-dynamic \
 	bin-ppc64le-dynamic \
 	bin-riscv64-dynamic \
+	bin-s390x-dynamic \
 	bin-sparc-dynamic \
 	bin-win32.exe \
 	bin-win64.exe \
@@ -39,6 +40,7 @@ EXTRA_DIST = \
 	lib-ppc64le.so \
 	lib-mipsel.so \
 	lib-riscv64.so \
+	lib-s390x.so \
 	lib-sparc.so \
 	lib-win32.dll \
 	lib-win64.dll \