Enable rpm builds and add archs

1. Add nfpm configuration for rpm builds.
2. Add x86_64 and s390x architectures.
3. Skip main.go check as there are several.
4. Rename deprecated `folder` to `directory`.

Tested with
```
goreleaser release --clean --snapshot --rm-dist --verbose --skip docker,homebrew
```

Signed-off-by: Sebastian Mitterle <[email protected]>

.goreleaser.yml

@@ -3,6 +3,7 @@ project_name: govmomi
 
 builds:
   - id: govc
+    no_main_check: true
     goos: &goos-defs
       - linux
       - darwin
@@ -13,6 +14,8 @@ builds:
       - arm
       - arm64
       - mips64le
+      - 386
+      - s390x
     env:
       - CGO_ENABLED=0
       - PKGPATH=github.com/vmware/govmomi/govc/flags
@@ -21,6 +24,7 @@ builds:
     ldflags:
       - "-X {{.Env.PKGPATH}}.BuildVersion={{.Version}} -X {{.Env.PKGPATH}}.BuildCommit={{.ShortCommit}} -X {{.Env.PKGPATH}}.BuildDate={{.Date}}"
   - id: vcsim
+    no_main_check: true
     goos: *goos-defs
     goarch: *goarch-defs
     env:
@@ -30,6 +34,17 @@ builds:
     ldflags:
       - "-X main.buildVersion={{.Version}} -X main.buildCommit={{.ShortCommit}} -X main.buildDate={{.Date}}"
 
+nfpms:
+  - package_name: govmomi
+    builds:
+      - govc
+    homepage: https://github.com/vmware/govmomi
+    maintainer: Doug MacEachern <[email protected]>
+    description: |-
+      vSphere CLI
+    formats:
+      - rpm
+
 archives:
   - id: govcbuild
     builds:
@@ -90,7 +105,7 @@ brews:
     commit_author:
       name: Alfred the Narwhal
       email: [email protected]
-    folder: Formula
+    directory: Formula
     homepage: "https://github.com/vmware/govmomi/blob/main/govc/README.md"
     description: "govc is a vSphere CLI built on top of govmomi."
     test: |
@@ -110,7 +125,7 @@ brews:
     commit_author:
       name: Alfred the Narwhal
       email: [email protected]
-    folder: Formula
+    directory: Formula
     homepage: "https://github.com/vmware/govmomi/blob/main/vcsim/README.md"
     description: "vcsim is a vSphere API simulator built on top of govmomi."
     test: |