[openssl] builtin: destination of include files was not correct

Compilation with builtin_openssl probably just worked fine because it picked system-wide openssl headers rather than the builtin ones.

Found out while investigating failures in #21947

Author: ferdymercury

builtins/openssl/CMakeLists.txt

@@ -39,7 +39,8 @@ endif()
 
 ExternalProject_Add(OPENSSL
   URL ${OPENSSL_URL} URL_HASH ${OPENSSL_URLHASH}
-  CONFIGURE_COMMAND ${OPENSSL_CONFIG_CMD} no-shared --prefix=<INSTALL_DIR>
+  INSTALL_DIR ${OPENSSL_PREFIX}
+  CONFIGURE_COMMAND ${OPENSSL_CONFIG_CMD} no-shared --prefix=<INSTALL_DIR> --openssldir=<INSTALL_DIR>
   BUILD_COMMAND make -j1 CC=${CMAKE_C_COMPILER}\ -fPIC\ ${OSX_SYSROOT}
   INSTALL_COMMAND make install_sw
   BUILD_IN_SOURCE 1