ShaderLang.h contains declaration for `ShLink` function which is never
defined.
See this grep output:
$grep -Hrn 'ShLink'
glslang/Public/ShaderLang.h:206:SH_IMPORT_EXPORT int ShLink(
glslang/Public/ShaderLang.h:214:SH_IMPORT_EXPORT int ShLinkExt(
glslang/MachineIndependent/ShaderLang.cpp:1268:int ShLinkExt(
