When liblzfe (Apple LZFSE compression library) is present
(for example installed via 'brew') on Darwin, QEMU build
fails as:

  Has header "lzfse.h" : YES
  Library lzfse found: YES

    Dependencies
      lzo support                  : NO
      snappy support               : NO
      bzip2 support                : YES
      lzfse support                : YES
      zstd support                 : YES 1.5.2

    User defined options
      dmg                          : enabled
      lzfse                        : enabled

  [221/903] Compiling C object libblock.fa.p/block_dmg-lzfse.c.o
  FAILED: libblock.fa.p/block_dmg-lzfse.c.o
  /opt/homebrew/Cellar/lzfse/1.0/include/lzfse.h:56:43: error: this function declaration is not a prototype [-Werror,-Wstrict-prototypes]
  LZFSE_API size_t lzfse_encode_scratch_size();
                                            ^
                                             void
  /opt/homebrew/Cellar/lzfse/1.0/include/lzfse.h:94:43: error: this function declaration is not a prototype [-Werror,-Wstrict-prototypes]
  LZFSE_API size_t lzfse_decode_scratch_size();
                                            ^
                                             void
  2 errors generated.
  ninja: build stopped: subcommand failed.

This issue has been reported in the lzfse project in 2016:
https://github.com/lzfse/lzfse/issues/3#issuecomment-226574719



Since the project seems unmaintained, simply ignore the
strict-prototypes warning check for the <lzfse.h> header,
similarly to how we deal with the GtkItemFactoryCallback
prototype from <gtk/gtkitemfactory.h>, indirectly included
by <gtk/gtk.h>.

Cc: Julio Faracco <jcfaracco@gmail.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Stefan Weil <sw@weilnetz.de>
Message-Id: <20230327151349.97572-1-philmd@linaro.org>