Specify layout index in shader

shaders/debayer.frag

@@ -3,7 +3,7 @@
 uniform sampler2D qt_Texture0;
 in vec2 qt_TexCoord0;
 in vec2 center;
-out vec4 color;
+layout(location = 0) out vec4 color;
 
 #define f(x, y) texelFetch(qt_Texture0, icenter + ivec2(x, y), 0).r
 

shaders/image.frag

@@ -7,7 +7,7 @@ uniform bool invert;
 uniform bool srgb;
 uniform vec3 whiteBalance;
 in vec2 qt_TexCoord0;
-out vec4 color;
+layout(location = 0) out vec4 color;
 
 vec3 Linear2sRGB(vec3 color)
 {

shaders/thumb.frag

@@ -4,7 +4,7 @@ uniform sampler2DArray qt_Texture0;
 uniform vec3 mtf_param;
 uniform bool invert;
 in vec3 qt_TexCoord0;
-out vec4 color;
+layout(location = 0) out vec4 color;
 
 vec4 MTF(vec4 x, vec3 m)
 {