Add CURL and OpenSSL the new way

deps/OpenSSL/OpenSSL.cmake

@@ -0,0 +1,32 @@
+
+include(ProcessorCount)
+ProcessorCount(NPROC)
+
+set(_cross_arch "")
+set(_cross_comp_prefix_line "")
+if (CMAKE_CROSSCOMPILING)
+    set(_cross_comp_prefix_line "--cross-compile-prefix=${TOOLCHAIN_PREFIX}")
+
+    if (${CMAKE_SYSTEM_PROCESSOR} STREQUAL "aarch64" OR ${CMAKE_SYSTEM_PROCESSOR} STREQUAL "arm64")
+        set(_cross_arch "linux-aarch64")
+    elseif (${CMAKE_SYSTEM_PROCESSOR} STREQUAL "armhf") # For raspbian
+        # TODO: verify
+        set(_cross_arch "linux-armv4")
+    endif ()
+endif ()
+
+ExternalProject_Add(dep_OpenSSL
+    EXCLUDE_FROM_ALL ON
+    URL "https://github.com/openssl/openssl/archive/OpenSSL_1_1_0l.tar.gz"
+    URL_HASH SHA256=e2acf0cf58d9bff2b42f2dc0aee79340c8ffe2c5e45d3ca4533dd5d4f5775b1d
+    BUILD_IN_SOURCE ON
+    CONFIGURE_COMMAND ./Configure ${_cross_arch}
+        "--prefix=${DESTDIR}/usr/local"
+        ${_cross_comp_prefix_line}
+        no-shared
+        no-ssl3-method
+        no-dynamic-engine
+        -Wa,--noexecstack
+    BUILD_COMMAND make depend && make "-j${NPROC}"
+    INSTALL_COMMAND make install_sw
+)