rke2: build with goboring library (#393009)

Use the FIPS Compatible boringcrypto Go compiler. This version of Go
replaces the standard Go crypto libraries with the FIPS validated
BoringCrypto module. Using a validated compiler is a requirement for
FIPS 140-2 Enablement of the RKE2 package.

pkgs/applications/networking/cluster/rke2/builder.nix

@@ -74,6 +74,9 @@ let
       lvm2 # dmsetup
     ];
 
+    # Passing boringcrypto to GOEXPERIMENT variable to build with goboring library
+    GOEXPERIMENT = "boringcrypto";
+
     # See: https://github.com/rancher/rke2/blob/e7f87c6dd56fdd76a7dab58900aeea8946b2c008/scripts/build-binary#L27-L38
     ldflags = [
       "-w"
@@ -120,6 +123,14 @@ let
 
     doCheck = false;
 
+    doInstallCheck = true;
+    installCheckPhase = ''
+      runHook preInstallCheck
+      # Verify that the binary uses BoringCrypto
+      go tool nm $out/bin/.rke2-wrapped | grep '_Cfunc__goboringcrypto_' > /dev/null
+      runHook postInstallCheck
+    '';
+
     passthru = {
       inherit updateScript;
       tests =