gnu: QEMU: Fix compatibility with Meson 0.58.

* gnu/packages/patches/qemu-meson-compat.patch: New file.
* gnu/local.mk (dist_patch_DATA): Adjust accordingly.
* gnu/packages/virtualization.scm (qemu)[source](patches): Add it.

gnu/local.mk

@@ -1623,6 +1623,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/pypy3-7.3.1-fix-tests.patch		\
   %D%/packages/patches/qemu-build-info-manual.patch		\
   %D%/packages/patches/qemu-CVE-2021-20203.patch		\
+  %D%/packages/patches/qemu-meson-compat.patch			\
   %D%/packages/patches/qemu-glibc-2.27.patch 			\
   %D%/packages/patches/qemu-glibc-2.30.patch 			\
   %D%/packages/patches/qpdfview-qt515-compat.patch		\

gnu/packages/patches/qemu-meson-compat.patch

@@ -0,0 +1,27 @@
+Fix a build failure that occurs with newer versions of Meson when
+gdbus-codegen is unavailable.
+
+Taken from upstream:
+https://gitlab.com/qemu-project/qemu/-/commit/5ecfb76ccc056eb6127e44268e475827ae73b9e0
+
+diff --git a/configure b/configure
+--- a/configure
++++ b/configure
+@@ -3341,7 +3341,7 @@ if ! test "$gio" = "no"; then
+         gio_cflags=$($pkg_config --cflags gio-2.0)
+         gio_libs=$($pkg_config --libs gio-2.0)
+         gdbus_codegen=$($pkg_config --variable=gdbus_codegen gio-2.0)
+-        if [ ! -x "$gdbus_codegen" ]; then
++        if ! has "$gdbus_codegen"; then
+             gdbus_codegen=
+         fi
+         # Check that the libraries actually work -- Ubuntu 18.04 ships
+@@ -5704,6 +5704,8 @@ if test "$gio" = "yes" ; then
+     echo "CONFIG_GIO=y" >> $config_host_mak
+     echo "GIO_CFLAGS=$gio_cflags" >> $config_host_mak
+     echo "GIO_LIBS=$gio_libs" >> $config_host_mak
++fi
++if test "$gdbus_codegen" != "" ; then
+     echo "GDBUS_CODEGEN=$gdbus_codegen" >> $config_host_mak
+ fi
+ echo "CONFIG_TLS_PRIORITY=\"$tls_priority\"" >> $config_host_mak

gnu/packages/virtualization.scm

@@ -152,6 +152,7 @@
         (base32
          "1f9hz8rf12jm8baa7kda34yl4hyl0xh0c4ap03krfjx23i3img47"))
        (patches (search-patches "qemu-CVE-2021-20203.patch"
+                                "qemu-meson-compat.patch"
                                 "qemu-build-info-manual.patch"))
        (modules '((guix build utils)))
        (snippet