Fix the shader to be compatible with GLSL 1.2

src/video_core/renderer_opengl/gl_shaders.h

@@ -7,19 +7,16 @@
 namespace GLShaders {
 
 const char g_vertex_shader[] = R"(
-#version 130
+#version 120
-
 in vec2 vert_position;
 in vec2 vert_tex_coord;
-out vec2 frag_tex_coord;
+varying out vec2 frag_tex_coord;
-
 // This is a truncated 3x3 matrix for 2D transformations:
 // The upper-left 2x2 submatrix performs scaling/rotation/mirroring.
 // The third column performs translation.
 // The third row could be used for projection, which we don't need in 2D. It hence is assumed to
 // implicitly be [0, 0, 1]
 uniform mat3x2 modelview_matrix;
-
 void main() {
     // Multiply input position by the rotscale part of the matrix and then manually translate by
     // the last column. This is equivalent to using a full 3x3 matrix and expanding the vector
@@ -30,15 +27,12 @@ void main() {
 )";
 
 const char g_fragment_shader[] = R"(
-#version 130
+#version 120
-
+varying in vec2 frag_tex_coord;
-in vec2 frag_tex_coord;
+varying out vec4 color;
-out vec4 color;
-
 uniform sampler2D color_texture;
-
 void main() {
-    color = texture(color_texture, frag_tex_coord);
+    color = texture2D(color_texture, frag_tex_coord);
 }
 )";