Hello-

While working on adding a new option, I noticed there are some options
(e.g. -fdiagnostics-format) that use the two-column form of the option
description, but separate the first column with space(s) rather than a
tab. This results in the help output looking a bit redundant, since the
option name is repeated:

$ for f in common optimizers params target warnings; do gcc --help=$f; done |
  grep -E '^[ ]*(-[^ ]*)[ ]+\1' | sort

  -Walloc-size-larger-than=   -Walloc-size-larger-than=<bytes> Warn for calls to allocation functions that attempt to allocate objects larger than
  -Walloc-zero                -Walloc-zero Warn for calls to allocation functions that specify zero bytes.
  -Wno-alloc-size-larger-than -Wno-alloc-size-larger-than Disable Walloc-size-larger-than= warning.  Equivalent to Walloc-size-larger-
  -Wno-alloca-larger-than     -Wno-alloca-larger-than Disable Walloca-larger-than= warning.  Equivalent to Walloca-larger-than=<SIZE_MAX> or larger.
  -Wno-vla-larger-than        -Wno-vla-larger-than Disable Wvla-larger-than= warning.  Equivalent to Wvla-larger-than=<SIZE_MAX> or larger.  Same as
  -fdebug-prefix-map=         -fdebug-prefix-map=<old>=<new> Map one directory name to another in debug information.
  -fdiagnostics-format=       -fdiagnostics-format=[text|json] Select output format.
  -fdisable-                  -fdisable-[tree|rtl|ipa]-<pass>=range1+range2 disables an optimization pass.
  -fenable-                   -fenable-[tree|rtl|ipa]-<pass>=range1+range2 enables an optimization pass.
  -ffile-prefix-map=          -ffile-prefix-map=<old>=<new> Map one directory name to another in compilation result.
  -finstrument-functions-exclude-file-list= -finstrument-functions-exclude-file-list=filename,...  Do not instrument functions listed in files.
  -finstrument-functions-exclude-function-list= -finstrument-functions-exclude-function-list=name,...  Do not instrument listed functions.
  -foffload-abi=              -foffload-abi=[lp64|ilp32]     Set the ABI to use in an offload compiler.
  -foffload=                  -foffload=<targets>=<options>  Specify offloading targets and options for them.

Is this something that would be desirable to change for GCC 10? Attached
patch would do so, and the output would become instead:

  -Walloc-size-larger-than=<bytes> Warn for calls to allocation functions that attempt to allocate objects larger than the specified number of bytes.
  -Walloc-zero                Warn for calls to allocation functions that specify zero bytes.
  -Wno-alloc-size-larger-than Disable Walloc-size-larger-than= warning.  Equivalent to Walloc-size-larger-than=<SIZE_MAX> or larger.  Same as -Walloc-size-larger-than=.
  -Wno-alloca-larger-than     Disable Walloca-larger-than= warning.  Equivalent to Walloca-larger-than=<SIZE_MAX> or larger.  Same as -Walloca-larger-than=.
  -Wno-vla-larger-than        Disable Wvla-larger-than= warning.  Equivalent to Wvla-larger-than=<SIZE_MAX> or larger.  Same as -Wvla-larger-than=.
  -fdebug-prefix-map=<old>=<new> Map one directory name to another in debug information.
  -fdiagnostics-format=[text|json] Select output format.
  -fdisable-[tree|rtl|ipa]-<pass>=range1+range2 Disable an optimization pass.
  -fenable-[tree|rtl|ipa]-<pass>=range1+range2 Enable an optimization pass.
  -ffile-prefix-map=<old>=<new> Map one directory name to another in compilation result.
  -finstrument-functions-exclude-file-list=filename,... Do not instrument functions listed in files.
  -finstrument-functions-exclude-function-list=name,... Do not instrument listed functions.
  -foffload-abi=[lp64|ilp32]  Set the ABI to use in an offload compiler.
  -foffload=<targets>=<options> Specify offloading targets and options for them.


For the most part it is just changing spaces to tabs, although in some cases
the two-column form was redundant so I removed the option name from the
beginning of the description instead.

Bootstrapped and regtested on x86-64 linux also. One test failed because it
was explicitly looking for the old output; modified that test too.

-Lewis