boot: Build with -flto=auto if available

Without this, we may get the following warning with gcc-12:
    lto-wrapper: warning: using serial compilation of 2 LTRANS jobs

diff --git a/src/boot/efi/meson.build b/src/boot/efi/meson.build
index 299a01b9be7eac4e69d39c10e5d0c857c02a462e..e17669478f70abd24d9f2cb6d1dc5f5580f482bf 100644 (file)
--- a/src/boot/efi/meson.build
+++ b/src/boot/efi/meson.build
@@ -223,7 +223,7 @@ if get_option('b_ndebug') == 'true' or (
         efi_cflags += ['-DNDEBUG']
 endif
 if get_option('b_lto')
-        efi_cflags += ['-flto']
+        efi_cflags += cc.has_argument('-flto=auto') ? ['-flto=auto'] : ['-flto']
 endif
 
 foreach arg : get_option('c_args')