Remove ExcludeArch but only compile on supported architectures

ring-fix-metadata-auto.diff

@@ -1,5 +1,5 @@
 --- ring-0.16.20/Cargo.toml	2021-02-01T22:20:41+00:00
-+++ ring-0.16.20/Cargo.toml	2023-03-18T22:05:06.357486+00:00
++++ ring-0.16.20/Cargo.toml	2023-04-01T14:08:54.743609+00:00
 @@ -60,10 +60,6 @@
  std = ["alloc"]
  test_logging = []

ring-fix-metadata.diff

@@ -1,5 +1,5 @@
 --- ring-0.16.20/Cargo.toml	2021-02-01T22:20:41+00:00
-+++ ring-0.16.20/Cargo.toml	2023-03-18T22:06:09.210728+00:00
++++ ring-0.16.20/Cargo.toml	2023-04-01T14:09:25.801749+00:00
 @@ -23,25 +23,10 @@
  readme = "doc/link-to-readme.md"
  keywords = ["crypto", "cryptography", "rand", "ECC", "RSA"]

rust-ring.spec

@@ -4,6 +4,10 @@
 
 %global crate ring
 
+# compile and run tests only on supported architectures
+# https://bugzilla.redhat.com/show_bug.cgi?id=1869980
+%global supported_arches x86_64 %{ix86} aarch64 %{arm}
+
 Name:           rust-ring
 Version:        0.16.20
 Release:        %autorelease
@@ -20,10 +24,6 @@ Patch:          ring-fix-metadata-auto.diff
 # * set package.license in metadata to match package license
 Patch:          ring-fix-metadata.diff
 
-# * ring does not support ppc64le and s390x:
-#   https://bugzilla.redhat.com/show_bug.cgi?id=1869980
-ExcludeArch:    ppc64le s390x
-
 BuildRequires:  rust-packaging >= 21
 
 %global _description %{expand:
@@ -161,17 +161,21 @@ use the "wasm32_c" feature of the "%{crate}" crate.
 %cargo_generate_buildrequires
 
 %build
+%ifarch %{supported_arches}
 %cargo_build
+%endif
 
 %install
 %cargo_install
 
 %if %{with check}
+%ifarch %{supported_arches}
 %check
 # * files needed for integration tests are not included in published crates
 %cargo_test -- --lib
 %cargo_test -- --doc
 %endif
+%endif
 
 %changelog
 %autochangelog

rust2rpm.conf

@@ -0,0 +1,6 @@
+[DEFAULT]
+supported-arches =
+  x86_64
+  %{ix86}
+  aarch64
+  %{arm}