glsl: silence unused var warnings

src/mesa/shader/slang/slang_mem.c

@@ -184,6 +184,7 @@ _slang_realloc(void *oldBuffer, GLuint oldSize, GLuint newSize)
 #else
    GET_CURRENT_CONTEXT(ctx);
    slang_mempool *pool = (slang_mempool *) ctx->Shader.MemPool;
+   (void) pool;
 
    if (newSize < oldSize) {
       return oldBuffer;
@@ -235,6 +236,7 @@ _slang_free(void *addr)
    if (addr) {
       GET_CURRENT_CONTEXT(ctx);
       slang_mempool *pool = (slang_mempool *) ctx->Shader.MemPool;
+      (void) pool;
       ASSERT(is_valid_address(pool, addr));
    }
 #endif