testgles2_sdf: Call correct function to get shader info log

(cherry picked from commit b8c88cc58423b7e654b18fdaf1aab5a343114586)

test/testgles2_sdf.c

@@ -151,7 +151,7 @@ process_shader(GLuint *shader, const char * source, GLint shader_type)
 
     /* Dump debug info (source and log) if compilation failed. */
     if (status != GL_TRUE) {
-        ctx.glGetProgramInfoLog(*shader, sizeof(buffer), &length, &buffer[0]);
+        ctx.glGetShaderInfoLog(*shader, sizeof(buffer), &length, &buffer[0]);
         buffer[length] = '\0';
         SDL_Log("Shader compilation failed: %s", buffer);fflush(stderr);
         quit(-1);