[llvm-objdump] Remove Generic Options group from help text output

Reapply 7368624 after revert and fix

Looking at other tools using tablegen for help output, general options
like --help are not separated from other options. This change removes
the "Generic Options" option group so the options are listed together.
the macho specific option group is left unaffected.

The test help.test was modified to reflect this change.

Differential Revision: https://reviews.llvm.org/D101652

Author: gbreynoo

llvm/test/tools/llvm-objdump/help.test

@@ -3,12 +3,14 @@ RUN: llvm-objdump --help-hidden | FileCheck --check-prefix=HIDDEN %s
 
 CHECK: OVERVIEW: llvm object file dumper
 CHECK: USAGE: llvm-objdump{{(.exe)?}} [options] <input object files>{{$}}
-CHECK: Generic Options:
+CHECK: OPTIONS:
 CHECK-NOT: {{ -w }}
+CHECK: llvm-objdump MachO Specific Options:
 CHECK: @FILE
 
 HIDDEN: OVERVIEW: llvm object file dumper
 HIDDEN: USAGE: llvm-objdump{{(.exe)?}} [options] <input object files>{{$}}
-HIDDEN: Generic Options:
+HIDDEN: OPTIONS:
 HIDDEN: {{ -w }}
+HIDDEN: llvm-objdump MachO Specific Options:
 HIDDEN: @FILE