Conditionalize baseline ISA

Related: RHEL-175607

golang.spec

@@ -92,6 +92,20 @@
 %global gohostarch  s390x
 %endif
 
+# Set the RHEL architecture baseline.
+%if 0%{?rhel} < 9
+%global goamd64 v1
+%global goppc64 power8
+%else
+%if 0%{?rhel} < 10
+%global goamd64 v2
+%global goppc64 power8
+%else
+%global goamd64 v3
+%global goppc64 power9
+%endif
+%endif
+
 %global go_api 1.26
 %global go_version 1.26.3
 %global version %{go_version}
@@ -275,6 +289,13 @@ popd
 
 sed -i '1s/$/ (%{?rhel:Red Hat} %{version}-%{release})/' VERSION
 
+# Historically the ISA baselines have been set in modify-go.env.patch.
+# This will prevent us sharing a specfile across major RHEL versions.
+# As such, we must override the baselines set in the patch file.
+sed -iE "s/^.*baseline for RHEL.*$//" go.env
+sed -i "s/GOAMD64=.*/GOAMD64=%{goamd64}/" go.env
+sed -i "s/GOPPC64=.*/GOPPC64=%{goppc64}/" go.env
+
 cp %{SOURCE2} ./src/runtime/
 # Delete the bundled race detector objects.
 find ./src/runtime/race/ -name "race_*.syso" -exec rm {} \;