Needed to use system's glslang rather than bundled.
https://github.com/Tencent/ncnn/issues/2622
--- a/src/gpu.cpp
+++ b/src/gpu.cpp
@@ -23,3 +23,3 @@
 #include "glslang/SPIRV/GlslangToSpv.h"
-#include "glslang/glslang/Public/ShaderLang.h"
+#include "glslang/Public/ShaderLang.h"