CMake: Don't build non-crypto when a subproject

When building Mbed Crypto as a subproject, don't add targets for
libmbedx509 or libmbedtls, as the parent project should build these. The
parent project will define USE_CRYPTO_SUBMODULE variable when using Mbed
Crypto as a submodule, so we can depend on that variable to control whether
or not we build non-crypto libraries.
diff --git a/library/CMakeLists.txt b/library/CMakeLists.txt
index 04e404c..ba137b9 100644
--- a/library/CMakeLists.txt
+++ b/library/CMakeLists.txt
@@ -147,17 +147,23 @@
     set_target_properties(${mbedcrypto_static_target} PROPERTIES OUTPUT_NAME mbedcrypto)
     target_link_libraries(${mbedcrypto_static_target} ${libs})
 
-    add_library(${mbedx509_static_target} STATIC ${src_x509})
-    set_target_properties(${mbedx509_static_target} PROPERTIES OUTPUT_NAME mbedx509)
-    target_link_libraries(${mbedx509_static_target} ${libs} ${mbedcrypto_static_target})
+    if(USE_CRYPTO_SUBMODULE)
+        install(TARGETS ${mbedcrypto_static_target}
+                DESTINATION ${LIB_INSTALL_DIR}
+                PERMISSIONS OWNER_READ OWNER_WRITE OWNER_EXECUTE GROUP_READ GROUP_EXECUTE WORLD_READ WORLD_EXECUTE)
+    else()
+        add_library(${mbedx509_static_target} STATIC ${src_x509})
+        set_target_properties(${mbedx509_static_target} PROPERTIES OUTPUT_NAME mbedx509)
+        target_link_libraries(${mbedx509_static_target} ${libs} ${mbedcrypto_static_target})
 
-    add_library(${mbedtls_static_target} STATIC ${src_tls})
-    set_target_properties(${mbedtls_static_target} PROPERTIES OUTPUT_NAME mbedtls)
-    target_link_libraries(${mbedtls_static_target} ${libs} ${mbedx509_static_target})
+        add_library(${mbedtls_static_target} STATIC ${src_tls})
+        set_target_properties(${mbedtls_static_target} PROPERTIES OUTPUT_NAME mbedtls)
+        target_link_libraries(${mbedtls_static_target} ${libs} ${mbedx509_static_target})
 
-    install(TARGETS ${mbedtls_static_target} ${mbedx509_static_target} ${mbedcrypto_static_target}
-            DESTINATION ${LIB_INSTALL_DIR}
-            PERMISSIONS OWNER_READ OWNER_WRITE OWNER_EXECUTE GROUP_READ GROUP_EXECUTE WORLD_READ WORLD_EXECUTE)
+        install(TARGETS ${mbedtls_static_target} ${mbedx509_static_target} ${mbedcrypto_static_target}
+                DESTINATION ${LIB_INSTALL_DIR}
+                PERMISSIONS OWNER_READ OWNER_WRITE OWNER_EXECUTE GROUP_READ GROUP_EXECUTE WORLD_READ WORLD_EXECUTE)
+    endif()
 endif(USE_STATIC_MBEDTLS_LIBRARY)
 
 if(USE_SHARED_MBEDTLS_LIBRARY)
@@ -165,20 +171,33 @@
     set_target_properties(mbedcrypto PROPERTIES VERSION 2.14.0 SOVERSION 3)
     target_link_libraries(mbedcrypto ${libs})
 
-    add_library(mbedx509 SHARED ${src_x509})
-    set_target_properties(mbedx509 PROPERTIES VERSION 2.14.0 SOVERSION 0)
-    target_link_libraries(mbedx509 ${libs} mbedcrypto)
+    if(USE_CRYPTO_SUBMODULE)
+        install(TARGETS mbedcrypto
+                DESTINATION ${LIB_INSTALL_DIR}
+                PERMISSIONS OWNER_READ OWNER_WRITE OWNER_EXECUTE GROUP_READ GROUP_EXECUTE WORLD_READ WORLD_EXECUTE)
+    else()
+        add_library(mbedx509 SHARED ${src_x509})
+        set_target_properties(mbedx509 PROPERTIES VERSION 2.14.0 SOVERSION 0)
+        target_link_libraries(mbedx509 ${libs} mbedcrypto)
 
-    add_library(mbedtls SHARED ${src_tls})
-    set_target_properties(mbedtls PROPERTIES VERSION 2.14.0 SOVERSION 12)
-    target_link_libraries(mbedtls ${libs} mbedx509)
+        add_library(mbedtls SHARED ${src_tls})
+        set_target_properties(mbedtls PROPERTIES VERSION 2.14.0 SOVERSION 12)
+        target_link_libraries(mbedtls ${libs} mbedx509)
 
-    install(TARGETS mbedtls mbedx509 mbedcrypto
-            DESTINATION ${LIB_INSTALL_DIR}
-            PERMISSIONS OWNER_READ OWNER_WRITE OWNER_EXECUTE GROUP_READ GROUP_EXECUTE WORLD_READ WORLD_EXECUTE)
+        install(TARGETS mbedtls mbedx509 mbedcrypto
+                DESTINATION ${LIB_INSTALL_DIR}
+                PERMISSIONS OWNER_READ OWNER_WRITE OWNER_EXECUTE GROUP_READ GROUP_EXECUTE WORLD_READ WORLD_EXECUTE)
+    endif()
 endif(USE_SHARED_MBEDTLS_LIBRARY)
 
-add_custom_target(lib DEPENDS mbedcrypto mbedx509 mbedtls)
-if(USE_STATIC_MBEDTLS_LIBRARY AND USE_SHARED_MBEDTLS_LIBRARY)
-    add_dependencies(lib mbedcrypto_static mbedx509_static mbedtls_static)
+if(USE_CRYPTO_SUBMODULE)
+    add_custom_target(crypto_lib DEPENDS mbedcrypto)
+    if(USE_STATIC_MBEDTLS_LIBRARY AND USE_SHARED_MBEDTLS_LIBRARY)
+        add_dependencies(crypto_lib mbedcrypto_static)
+    endif()
+else()
+    add_custom_target(lib DEPENDS mbedcrypto mbedx509 mbedtls)
+    if(USE_STATIC_MBEDTLS_LIBRARY AND USE_SHARED_MBEDTLS_LIBRARY)
+        add_dependencies(lib mbedcrypto_static mbedx509_static mbedtls_static)
+    endif()
 endif()