CMake: use target_include_directories to expose includes

This makes glslang simpler to embed in larger projects.

SPIRV/CMakeLists.txt

@@ -43,6 +43,7 @@ endif(ENABLE_NV_EXTENSIONS)
 add_library(SPIRV ${LIB_TYPE} ${SOURCES} ${HEADERS})
 set_property(TARGET SPIRV PROPERTY FOLDER glslang)
 set_property(TARGET SPIRV PROPERTY POSITION_INDEPENDENT_CODE ON)
+target_include_directories(SPIRV PUBLIC ..)
 
 add_library(SPVRemapper ${LIB_TYPE} ${SPVREMAP_SOURCES} ${SPVREMAP_HEADERS})
 set_property(TARGET SPVRemapper PROPERTY FOLDER glslang)

glslang/CMakeLists.txt

@@ -84,6 +84,7 @@ add_library(glslang ${LIB_TYPE} ${BISON_GLSLParser_OUTPUT_SOURCE} ${SOURCES} ${H
 set_property(TARGET glslang PROPERTY FOLDER glslang)
 set_property(TARGET glslang PROPERTY POSITION_INDEPENDENT_CODE ON)
 target_link_libraries(glslang OGLCompiler OSDependent)
+target_include_directories(glslang PUBLIC ..)
 
 if(WIN32 AND BUILD_SHARED_LIBS)
     set_target_properties(glslang PROPERTIES PREFIX "")