dashboard: require at least Go 1.12 for aix builder

Fixes golang/go#30799

Change-Id: I0b3b53b715e2dc00f10548f74443224190003818
Reviewed-on: https://go-review.googlesource.com/c/build/+/167357
Reviewed-by: Bryan C. Mills <bcmills@google.com>
diff --git a/dashboard/builders_test.go b/dashboard/builders_test.go
index 19f8c5b..130e4dd 100644
--- a/dashboard/builders_test.go
+++ b/dashboard/builders_test.go
@@ -320,6 +320,14 @@
 		{b("freebsd-386-12_0", "go"), onlyPost},
 		{b("freebsd-386-12_0", "net"), onlyPost},
 
+		// AIX starts at Go 1.12
+		{b("aix-ppc64", "go"), onlyPost},
+		{b("aix-ppc64", "net"), onlyPost},
+		{b("aix-ppc64@go1.12", "go"), onlyPost},
+		{b("aix-ppc64@go1.12", "net"), onlyPost},
+		{b("aix-ppc64@go1.11", "go"), none},
+		{b("aix-ppc64@go1.11", "net"), none},
+
 		{b("linux-amd64-nocgo", "mobile"), none},
 
 		// The physical ARM Androids only runs "go":