[PATCH-for-8.0] block/dmg: Ignore C99 prototype declaration mismatch from <lzfse.h>

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

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>
---
 block/dmg-lzfse.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/block/dmg-lzfse.c b/block/dmg-lzfse.c
index 6798cf4fbf..0abc970bf6 100644
--- a/block/dmg-lzfse.c
+++ b/block/dmg-lzfse.c
@@ -23,7 +23,12 @@
  */
 #include "qemu/osdep.h"
 #include "dmg.h"
+
+/* Work around an -Wstrict-prototypes warning in LZFSE headers */
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wstrict-prototypes"
 #include <lzfse.h>
+#pragma GCC diagnostic pop
 
 static int dmg_uncompress_lzfse_do(char *next_in, unsigned int avail_in,
                                    char *next_out, unsigned int avail_out)
-- 
2.38.1