glsl: Fix (and validate) comment above glsl_type::name.

The comment above glsl_type::name claimed that it could sometimes be
NULL.  This was wrong--it is never NULL.  Many error handling paths
would segfault if it were.  (Anonymous structs are assigned names like
"#anon_struct_0001"--see the ast_struct_specifier constructor in
glsl_parser_extras.cpp.)

Fix the comment and add assertions to validate that it really is never
NULL.

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>

src/glsl/glsl_types.cpp

@@ -57,6 +57,7 @@ glsl_type::glsl_type(GLenum gl_type,
    length(0)
 {
    init_ralloc_type_ctx();
+   assert(name != NULL);
    this->name = ralloc_strdup(this->mem_ctx, name);
    /* Neither dimension is zero or both dimensions are zero.
     */
@@ -75,6 +76,7 @@ glsl_type::glsl_type(GLenum gl_type,
    length(0)
 {
    init_ralloc_type_ctx();
+   assert(name != NULL);
    this->name = ralloc_strdup(this->mem_ctx, name);
    memset(& fields, 0, sizeof(fields));
 }
@@ -91,6 +93,7 @@ glsl_type::glsl_type(const glsl_struct_field *fields, unsigned num_fields,
    unsigned int i;
 
    init_ralloc_type_ctx();
+   assert(name != NULL);
    this->name = ralloc_strdup(this->mem_ctx, name);
    this->fields.structure = ralloc_array(this->mem_ctx,
 					 glsl_struct_field, length);
@@ -114,6 +117,7 @@ glsl_type::glsl_type(const glsl_struct_field *fields, unsigned num_fields,
    unsigned int i;
 
    init_ralloc_type_ctx();
+   assert(name != NULL);
    this->name = ralloc_strdup(this->mem_ctx, name);
    this->fields.structure = ralloc_array(this->mem_ctx,
 					 glsl_struct_field, length);

src/glsl/glsl_types.h

@@ -132,8 +132,7 @@ struct glsl_type {
    /**
     * Name of the data type
     *
-    * This may be \c NULL for anonymous structures, for arrays, or for
-    * function types.
+    * Will never be \c NULL.
     */
    const char *name;