[gnome-shell] st: Fix generated GLSL dependency

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 15d74c9cd4f6a3792032b1b1e83f838b588b35ef
Author: Florian Müllner <fmuellner gnome org>
Date:   Fri Dec 20 20:54:07 2019 +0100

    st: Fix generated GLSL dependency
    
    StScrollViewFade depends on st-scroll-view-fade-generated.c, but
    that dependency isn't expressed to the build system; we just hope
    that the custom target runs before compiling the effect.
    
    Instead, add the generated source to the st target so the dependency
    is expressed properly.
    
    (The change from .c to .h is to prevent the file from being both
    included and compiled, resulting in a duplicated symbol)
    
    https://bugzilla.gnome.org/show_bug.cgi?id=789937

 src/st/meson.build           | 9 +++++----
 src/st/st-scroll-view-fade.c | 2 +-
 2 files changed, 6 insertions(+), 5 deletions(-)
---
diff --git a/src/st/meson.build b/src/st/meson.build
index 7ab203659b..452c30b99f 100644
--- a/src/st/meson.build
+++ b/src/st/meson.build
@@ -155,14 +155,15 @@ st_gir_sources = st_sources + st_headers + st_enums
 
 data_to_c = find_program(meson.source_root() + '/src/data-to-c.pl')
 
-custom_target('scroll-view-fade-glsl',
+glsl_sources = custom_target('scroll-view-fade-glsl',
   input: ['st-scroll-view-fade.glsl'],
-  output: ['st-scroll-view-fade-generated.c'],
-  build_by_default: true,
+  output: ['st-scroll-view-fade-generated.h'],
   capture: true,
   command: [data_to_c, '@INPUT@', 'st_scroll_view_fade_glsl']
 )
 
+st_nogir_sources = [glsl_sources]
+
 st_cflags = [
   '-I@0@/src'.format(meson.source_root()),
   '-I@0@'.format(meson.build_root()),
@@ -177,7 +178,7 @@ st_cflags = [
 
 # Currently meson requires a shared library for building girs
 libst = shared_library('st-1.0',
-  sources: st_gir_sources + croco_sources,
+  sources: st_gir_sources + st_nogir_sources + croco_sources,
   c_args: st_cflags,
   dependencies: [clutter_dep, gtk_dep, mutter_dep, libxml_dep, m_dep],
   build_rpath: mutter_typelibdir,
diff --git a/src/st/st-scroll-view-fade.c b/src/st/st-scroll-view-fade.c
index 8d473d3adf..656fa322fe 100644
--- a/src/st/st-scroll-view-fade.c
+++ b/src/st/st-scroll-view-fade.c
@@ -32,7 +32,7 @@
 
 #define DEFAULT_FADE_OFFSET 68.0f
 
-#include "st-scroll-view-fade-generated.c"
+#include "st-scroll-view-fade-generated.h"
 
 struct _StScrollViewFade
 {