ENH: robustness, consistency for wmake -show-api, -version

- add to wmakeFunctions to ensure it works even without 'make' being
  installed. Exit immediately after -show-api for consistency with
  -version.

foamEtcFile:
  - drop warnings for some old (pre-v1812) defunct options
    and simply flag as unknown options.
  - handle -version, --version as equivalent to -show-api

bin/foamEtcFile

@@ -7,7 +7,7 @@
 #    \\/     M anipulation  |
 #------------------------------------------------------------------------------
 #     Copyright (C) 2011-2016 OpenFOAM Foundation
-#     Copyright (C) 2017-2020 OpenCFD Ltd.
+#     Copyright (C) 2017-2021 OpenCFD Ltd.
 #------------------------------------------------------------------------------
 # License
 #     This file is part of OpenFOAM, distributed under GPL-3.0-or-later.
@@ -74,15 +74,16 @@ options:
   -with-api=NUM     Specify alternative api value to search with
   -quiet (-q)       Suppress all normal output
   -silent (-s)      Suppress stderr, except -csh-verbose, -sh-verbose output
+  -version | --version  Print version (same as -show-api)
   -help             Print the usage
 
 Locate user/group/other file as per '#includeEtc'
 
 Do not group single character options.
 Equivalent options:
-  |  -mode=MODE     |  -mode MODE     | -m MODE
-  |  -prefix=DIR    |  -prefix DIR    | -p DIR   [obsolete 1812]
-  |  -version=VER   |  -version VER   | -v VER   [obsolete 1812]
+  |  -mode=MODE     | -mode MODE  | -m MODE
+  |  -prefix=DIR    [obsolete 1812]
+  |  -version=VER   [obsolete 1812]
 
 Exit status
     0  when the file is found. Print resolved path to stdout.
@@ -149,7 +150,7 @@ do
     -h | -help*)
         printHelp
         ;;
-    -show-api)  # Show API and exit
+    -show-api | -version | --version)  # Show API and exit
         getApiInfo api
         exit $?
         ;;
@@ -202,25 +203,17 @@ do
     -s | -silent)
         optSilent=true
         ;;
-
     -etc=*)
         # FOAM_CONFIG_ETC for finding files. Empty unsets it (later)
         export FOAM_CONFIG_ETC="${1#*=}"
         ;;
-    -prefix=* | -version=*)
-        echo "ignored defunct option '${1%%=*}'" 1>&2
-        ;;
-    -p | -prefix | -v | -version)
-        # Ignored, but still need to check/discard its argument
-        [ "$#" -ge 2 ] || die "'$1' option requires an argument"
-        echo "ignored defunct option '$1'" 1>&2
-        shift
-        ;;
-
     --)
         shift
         break
         ;;
+    -prefix=* | -version=*)
+        echo "ignored defunct option '${1%%=*}'" 1>&2
+        ;;
     -*)
         die "unknown option: '$1'"
         ;;