RFR: 7903682: Misformatted --help message

[Jorn Vernee]

Fix some formatting issues in the `--help` message. The new message looks correct to me now:


> .\build\jextract\bin\jextract.bat --help
Usage: jextract <options> <header file>

Option                             Description
------                             -----------
-?, -h, --help                     print help
-D --define-macro <macro>=<value>  define <macro> to <value> (or 1 if <value> omitted)
-I, --include-dir <dir>            add directory to the end of the list of include search paths
--dump-includes <file>             dump included symbols into specified file
--header-class-name <name>         name of the generated header class. If this option is not
                                   specified, then header class name is derived from the header
                                   file name. For example, class "foo_h" for header "foo.h".
--include-function <name>          name of function to include
--include-constant <name>          name of macro or enum constant to include
--include-struct <name>            name of struct definition to include
--include-typedef <name>           name of type definition to include
--include-union <name>             name of union definition to include
--include-var <name>               name of global variable to include
-l, --library <libspec>            specify a shared library that should be loaded by the
                                   generated header class. If <libspec> starts with :, then
                                   what follows is interpreted as a library path. Otherwise,
                                   <libspec> denotes a library name. Examples:
                                      -l GL
                                      -l :libGL.so.1
                                      -l :/usr/lib/libGL.so.1
--use-system-load-library          libraries specified using -l are loaded in the loader symbol
                                   lookup (using either System::loadLibrary, or System::load).
                                   Useful if the libraries must be loaded from one of the paths
                                   in java.library.path.
--output <path>                    specify the directory to place generated files. If this
                                   option is not specified, then current directory is used.
--source                           generate java sources
-t, --target-package <package>     target package name for the generated classes. If this option
                                   is not specified, then unnamed package is used.
--version                          print version information and exit

-------------

Commit messages:
 - fix help message formatting

Changes: https://git.openjdk.org/jextract/pull/225/files
 Webrev: https://webrevs.openjdk.org/?repo=jextract&pr=225&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903682
  Stats: 4 lines in 1 file changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jextract/pull/225.diff
  Fetch: git fetch https://git.openjdk.org/jextract.git pull/225/head:pull/225

PR: https://git.openjdk.org/jextract/pull/225