meson: always combine directories with prefix

Meson allows directories such as "bindir" to be relative to the prefix.  Right
now configure is forcing an absolute path, but that is not really necessary:
just make sure all uses of the directory variables are prefixed appropriately.
Do the same also for the options that are custom for QEMU, i.e. docdir and
qemu_firmwarepath.

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

meson.build

@@ -1620,7 +1620,7 @@ config_host_data.set_quoted('CONFIG_PREFIX', get_option('prefix'))
 config_host_data.set_quoted('CONFIG_QEMU_CONFDIR', get_option('prefix') / qemu_confdir)
 config_host_data.set_quoted('CONFIG_QEMU_DATADIR', get_option('prefix') / qemu_datadir)
 config_host_data.set_quoted('CONFIG_QEMU_DESKTOPDIR', get_option('prefix') / qemu_desktopdir)
-config_host_data.set_quoted('CONFIG_QEMU_FIRMWAREPATH', get_option('qemu_firmwarepath'))
+config_host_data.set_quoted('CONFIG_QEMU_FIRMWAREPATH', get_option('prefix') / get_option('qemu_firmwarepath'))
 config_host_data.set_quoted('CONFIG_QEMU_HELPERDIR', get_option('prefix') / get_option('libexecdir'))
 config_host_data.set_quoted('CONFIG_QEMU_ICONDIR', get_option('prefix') / qemu_icondir)
 config_host_data.set_quoted('CONFIG_QEMU_LOCALEDIR', get_option('prefix') / get_option('localedir'))
@@ -3629,20 +3629,20 @@ endif
 summary_info = {}
 summary_info += {'Install prefix':    get_option('prefix')}
 summary_info += {'BIOS directory':    qemu_datadir}
-summary_info += {'firmware path':     get_option('qemu_firmwarepath')}
-summary_info += {'binary directory':  get_option('bindir')}
-summary_info += {'library directory': get_option('libdir')}
+summary_info += {'firmware path':     get_option('prefix') / get_option('qemu_firmwarepath')}
+summary_info += {'binary directory':  get_option('prefix') / get_option('bindir')}
+summary_info += {'library directory': get_option('prefix') / get_option('libdir')}
 summary_info += {'module directory':  qemu_moddir}
-summary_info += {'libexec directory': get_option('libexecdir')}
-summary_info += {'include directory': get_option('includedir')}
-summary_info += {'config directory':  get_option('sysconfdir')}
+summary_info += {'libexec directory': get_option('prefix') / get_option('libexecdir')}
+summary_info += {'include directory': get_option('prefix') / get_option('includedir')}
+summary_info += {'config directory':  get_option('prefix') / get_option('sysconfdir')}
 if targetos != 'windows'
-  summary_info += {'local state directory': get_option('localstatedir')}
-  summary_info += {'Manual directory':      get_option('mandir')}
+  summary_info += {'local state directory': get_option('prefix') / get_option('localstatedir')}
+  summary_info += {'Manual directory':      get_option('prefix') / get_option('mandir')}
 else
   summary_info += {'local state directory': 'queried at runtime'}
 endif
-summary_info += {'Doc directory':     get_option('docdir')}
+summary_info += {'Doc directory':     get_option('prefix') / get_option('docdir')}
 summary_info += {'Build directory':   meson.current_build_dir()}
 summary_info += {'Source path':       meson.current_source_dir()}
 summary_info += {'GIT submodules':    config_host['GIT_SUBMODULES']}