COMP: simplify openmp handling (#2617)

- remove old, unneeded -DUSE_OMP define.
- wmake -no-openmp option to add '~openmp' to WM_COMPILE_CONTROL

ENH: add bash completion handling for wmake

applications/test/openmp/Make/options

@@ -1,4 +1,4 @@
-EXE_INC = $(COMP_OPENMP) /* -UUSE_OMP */
+EXE_INC = $(COMP_OPENMP)
 
 /* Mostly do not need to explicitly link openmp libraries */
 /* EXE_LIBS = $(LINK_OPENMP) */

applications/test/openmp/Test-openmp.C

@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2017 OpenCFD Ltd.
+    Copyright (C) 2017-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -41,12 +41,6 @@ Description
 
 int main(int argc, char *argv[])
 {
-#if USE_OMP
-    std::cout << "USE_OMP defined (" << USE_OMP << ")\n";
-#else
-    std::cout << "USE_OMP undefined\n";
-#endif
-
 #if _OPENMP
     std::cout << "_OPENMP = " << _OPENMP << "\n\n";