[client] egl: switch to using GL_TEXTURE_EXTERNAL_OES for DMABUF

According to Erik @ NVidia the open source NVidia driver will not
create a EGLImage from a DMABUF if the target is not
GL_TEXTURE_EXTERNAL_OES. This change set converts the dmabuf texture
from GL_TEXTURE_2D to GL_TEXTURE_EXTERNAL_OES and at runtime performs a
global search & replace on fragment shaders as needed to remain
compatible, replacing `sampler2D` with `samplerExternalOES`.

Ref: https://github.com/NVIDIA/open-gpu-kernel-modules/discussions/243#discussioncomment-3283415

client/renderers/EGL/damage.c

@@ -76,7 +76,8 @@ bool egl_damageInit(EGL_Damage ** damage)
 
   if (!egl_shaderCompile((*damage)->shader,
         b_shader_damage_vert, b_shader_damage_vert_size,
-        b_shader_damage_frag, b_shader_damage_frag_size))
+        b_shader_damage_frag, b_shader_damage_frag_size,
+        false))
   {
     DEBUG_ERROR("Failed to compile the damage shader");
     return false;