[at-spi2-core/gnome-3-32] Fix meson.build for meson 0.50.0.

[Mike Gorse <mgorse src gnome org>]

commit e5c55c26a5d21fff1b88c90ee7aee4269788797c
Author: Tobias Stoeckmann <tobias stoeckmann org>
Date:   Tue Mar 12 11:46:24 2019 +0100

    Fix meson.build for meson 0.50.0.
    
    Since meson 0.50.0 it is not possible anymore to specify an
    absolute directory for subdir. To keep current functionality,
    use install_dir instead.
    
    atspi/meson.build:60:0: ERROR: Subdir keyword must not be an absolute path.
    
    Signed-off-by: Tobias Stoeckmann <tobias stoeckmann org>

 atspi/meson.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/atspi/meson.build b/atspi/meson.build
index b7a9357..2a6915d 100644
--- a/atspi/meson.build
+++ b/atspi/meson.build
@@ -57,7 +57,7 @@ atspi_headers = [
 
 atspi_includedir = join_paths(get_option('prefix'), get_option('includedir'), 'at-spi-2.0', 'atspi')
 
-install_headers(atspi_headers, subdir: atspi_includedir)
+install_headers(atspi_headers, install_dir: atspi_includedir)
 
 atspi_enums = gnome.mkenums('atspi-enum-types',
                             sources: [ 'atspi-constants.h', 'atspi-types.h' ],