Fix spirv backcompat

closes #3882

SPIRV/CMakeLists.txt

diff --git a/SPIRV/CMakeLists.txt b/SPIRV/CMakeLists.txt
index 4b3ec1e..d746839 100644
--- a/SPIRV/CMakeLists.txt
+++ b/SPIRV/CMakeLists.txt
@@ -91,6 +91,7 @@
 target_include_directories(SPIRV PUBLIC
     $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/..>
     $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>)
+glslang_only_export_explicit_symbols(SPIRV)
 
 if (ENABLE_SPVREMAPPER)
     add_library(SPVRemapper ${LIB_TYPE} ${SPVREMAP_SOURCES} ${SPVREMAP_HEADERS})
@@ -128,9 +129,7 @@
         install(TARGETS SPVRemapper EXPORT glslang-targets)
     endif()
 
-    if (NOT BUILD_SHARED_LIBS)
-        install(TARGETS SPIRV EXPORT glslang-targets)
-    endif()
+    install(TARGETS SPIRV EXPORT glslang-targets)
 
     install(FILES ${PUBLIC_HEADERS} DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/glslang/SPIRV/)
 endif()

glslang/stub.cpp

diff --git a/glslang/stub.cpp b/glslang/stub.cpp
index b9aec6d..9c286fb 100644
--- a/glslang/stub.cpp
+++ b/glslang/stub.cpp
@@ -32,6 +32,20 @@
 // POSSIBILITY OF SUCH DAMAGE.
 //
 
-// This empty source file exists to support building stubbed versions of
-// deprecated libraries which have been integrated into the main glslang
-// library. It should be deleted once the stub libraries are fully removed.
+#ifdef GLSLANG_IS_SHARED_LIBRARY
+#ifdef _WIN32
+#ifdef GLSLANG_EXPORTING
+#define STUB_EXPORT __declspec(dllexport)
+#else
+#define STUB_EXPORT __declspec(dllimport)
+#endif
+#endif
+#endif // GLSLANG_IS_SHARED_LIBRARY
+
+#ifndef STUB_EXPORT
+#define STUB_EXPORT
+#endif
+
+// Force stub library to export function to preserve backcompat.
+// https://github.com/KhronosGroup/glslang/issues/3882
+STUB_EXPORT int stub_library_function() { return 0; }