ShellPkg/UefiShellDebug1CommandsLib: sync Compress() definition with decl.

ShellPkg/UefiShellDebug1CommandsLib: sync Compress() definition with decl.

"Compress.h" declares the Compress() function as EFIAPI, but the
definition in "Compress.c" lacks EFIAPI.

GCC toolchains without LTO do not catch this error because "Compress.c"
does not include "Compress.h"; i.e. the declaration used by callers such
as "EfiCompress.c" is not actually matched against the function definition
at build time.

With LTO enabled, the mismatch is found -- however, as a warning only, due
to commit f8d0b9662993 ("BaseTools GCC5: disable warnings-as-errors for
now", 2016-08-03).

Include the header in the C file (which turns the issue into a hard build
error on all GCC toolchains), plus sync the declaration from the header
file to the C file. Finally, remove EFIAPI from both declaration and
definition -- this was the original intent of commit c4e74e9b814c
("ShellPkg/UefiShellDebug1CommandsLib: Remove unnecessary EFIAPI",
2016-10-09), but it missed the header file.

(Gary meant to address that omission in Oct 2017:

  [edk2] [PATCH] ShellPkg/UefiShellDebug1CommandsLib: Remove EFIAPI from
                 Compress()

  http://mid.mail-archive.com/20171026065329.32311-1-glin@suse.com

and Ray reviewed the patch, but then the patch was never committed.)

So do the sync and drop EFIAPI now.

This happens to fix the EFICOMPRESS shell command, when built with GCC for
X64.

Cc: Gary Lin <glin@suse.com>
Cc: Jaben Carsey <jaben.carsey@intel.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Fixes: c4e74e9b814cfb4b51cf832f3bb218cd2aba348b
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Gary Lin <glin@suse.com>
Reviewed-by: Jaben Carsey <jaben.carsey@intel.com>