[gnome-shell] build: Use multi-line string for embedded code

[Florian Müllner <fmuellner src gnome org>]

commit 0f61af6b8585bdc412414a291e2efde8a9b312c2
Author: Florian Müllner <fmuellner gnome org>
Date:   Tue Jun 28 18:59:05 2022 +0200

    build: Use multi-line string for embedded code
    
    Newer meson versions complain about newline characters in regular
    strings, so switch to a proper multi-line string.
    
    Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2350>

 meson.build | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
---
diff --git a/meson.build b/meson.build
index 354fbd6d87..bc0f62176f 100644
--- a/meson.build
+++ b/meson.build
@@ -157,9 +157,11 @@ cdata.set('HAVE_FDWALK',
 )
 
 polkit_has_autocleanup = cc.compiles(
-  '#define POLKIT_AGENT_I_KNOW_API_IS_SUBJECT_TO_CHANGE
+'''
+  #define POLKIT_AGENT_I_KNOW_API_IS_SUBJECT_TO_CHANGE
   #include <polkitagent/polkitagent.h>
-  void main(void) { g_autoptr(PolkitAgentListener) agent = NULL; }',
+  void main(void) { g_autoptr(PolkitAgentListener) agent = NULL; }
+''',
   dependencies: polkit_dep)
 cdata.set('HAVE_POLKIT_AUTOCLEANUP', polkit_has_autocleanup)