meson: sort existing compiler tests

The next patches will add more compiler tests.  Sort and group the
existing tests, keeping similar cc.has_* tests together and sorting them
alphabetically by macro name.  This should make it easier to look for
examples when adding new tests to meson.build.

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

meson.build

@@ -1253,16 +1253,19 @@ config_host_data.set('QEMU_VERSION_MAJOR', meson.project_version().split('.')[0]
 config_host_data.set('QEMU_VERSION_MINOR', meson.project_version().split('.')[1])
 config_host_data.set('QEMU_VERSION_MICRO', meson.project_version().split('.')[2])
 
+config_host_data.set('HAVE_HOST_BLOCK_DEVICE', have_host_block_device)
+
+# has_header
 config_host_data.set('HAVE_BTRFS_H', cc.has_header('linux/btrfs.h'))
 config_host_data.set('HAVE_DRM_H', cc.has_header('libdrm/drm.h'))
 config_host_data.set('HAVE_PTY_H', cc.has_header('pty.h'))
+config_host_data.set('HAVE_SYS_DISK_H', cc.has_header('sys/disk.h'))
 config_host_data.set('HAVE_SYS_IOCCOM_H', cc.has_header('sys/ioccom.h'))
 config_host_data.set('HAVE_SYS_KCOV_H', cc.has_header('sys/kcov.h'))
-config_host_data.set('HAVE_SYSTEM_FUNCTION', cc.has_function('system', prefix: '#include <stdlib.h>'))
-config_host_data.set('HAVE_HOST_BLOCK_DEVICE', have_host_block_device)
-config_host_data.set('HAVE_SYS_DISK_H', cc.has_header('sys/disk.h'))
 
+# has_function
 config_host_data.set('CONFIG_PREADV', cc.has_function('preadv', prefix: '#include <sys/uio.h>'))
+config_host_data.set('HAVE_SYSTEM_FUNCTION', cc.has_function('system', prefix: '#include <stdlib.h>'))
 
 ignored = ['CONFIG_QEMU_INTERP_PREFIX'] # actually per-target
 arrays = ['CONFIG_AUDIO_DRIVERS', 'CONFIG_BDRV_RW_WHITELIST', 'CONFIG_BDRV_RO_WHITELIST']