Add option to skip installation

As a static target, when included in other cmake projects, it is not needed to install these libraries and headers as part of this build, and just need to link to this.

CMakeLists.txt

@@ -6,6 +6,11 @@ set_property(GLOBAL PROPERTY USE_FOLDERS ON)
 # Adhere to GNU filesystem layout conventions
 include(GNUInstallDirs)
 
+option(SKIP_GLSLANG_INSTALL "Skip installation" ${SKIP_GLSLANG_INSTALL})
+if(NOT ${SKIP_GLSLANG_INSTALL})
+  set(ENABLE_GLSLANG_INSTALL ON)
+endif()
+
 option(ENABLE_AMD_EXTENSIONS "Enables support of AMD-specific extensions" ON)
 option(ENABLE_GLSLANG_BINARIES "Builds glslangValidator and spirv-remap" ON)