Prebuild aws-lc (#584)

Co-authored-by: Michael Graeb <[email protected]>

crt/CMakeLists.txt

@@ -32,15 +32,26 @@ if(UNIX AND NOT APPLE)
     option(USE_OPENSSL "Set this if you want to use your system's OpenSSL compatible libcrypto" OFF)
 
     if(NOT USE_OPENSSL)
-        set(DISABLE_GO ON CACHE BOOL "Build without using Go, we don't want the extra dependency")
-        set(BUILD_LIBSSL OFF CACHE BOOL "Don't need libssl, only need libcrypto")
+        include(AwsPrebuildDependency)
+
+        set(AWSLC_CMAKE_ARGUMENTS
+            -DDISABLE_GO=ON  # Build without using Go, we don't want the extra dependency
+            -DDISABLE_PERL=ON  # Build without using Perl, we don't want the extra dependency
+            -DBUILD_LIBSSL=OFF  # Don't need libssl, only need libcrypto
+            -DBUILD_TESTING=OFF
+        )
 
-        set(DISABLE_PERL ON CACHE BOOL "Build without using Perl, we don't want the extra dependency")
         if(CMAKE_C_COMPILER_ID MATCHES "GNU" AND CMAKE_C_COMPILER_VERSION VERSION_LESS "5.0")
-            set(MY_ASSEMBLER_IS_TOO_OLD_FOR_512AVX ON CACHE BOOL "Disable AVX512 on old GCC that not supports it")
+            # Disable AVX512 on old GCC that not supports it.
+            list(APPEND AWSLC_CMAKE_ARGUMENTS -DMY_ASSEMBLER_IS_TOO_OLD_FOR_512AVX=ON)
         endif()
 
-        add_subdirectory(aws-lc)
+        # s2n-tls uses libcrypto during its configuration, so we need to prebuild aws-lc.
+        aws_prebuild_dependency(
+            DEPENDENCY_NAME AWSLC
+            SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/aws-lc
+            CMAKE_ARGUMENTS ${AWSLC_CMAKE_ARGUMENTS}
+        )
     endif()
 
     set(UNSAFE_TREAT_WARNINGS_AS_ERRORS OFF CACHE BOOL "")