glsl2: check for _NumLinkedShaders being 0
Otherwise spring 0.82+.4.0 crashes when starting a game
because prog->_LinkedShaders[0] is NULL.
This also fixes piglit test cases glsl-link-empty-prog-0[12].
diff --git a/src/glsl/linker.cpp b/src/glsl/linker.cpp
index e0823c3..02c7c29 100644
--- a/src/glsl/linker.cpp
+++ b/src/glsl/linker.cpp
@@ -1476,7 +1476,7 @@
assign_uniform_locations(prog);
- if (prog->_LinkedShaders[0]->Type == GL_VERTEX_SHADER) {
+ if (prog->_NumLinkedShaders && prog->_LinkedShaders[0]->Type == GL_VERTEX_SHADER) {
/* FINISHME: The value of the max_attribute_index parameter is
* FINISHME: implementation dependent based on the value of
* FINISHME: GL_MAX_VERTEX_ATTRIBS. GL_MAX_VERTEX_ATTRIBS must be