Don't set ARCH_ID if it's already set

Usually it's unset, but depends toolchain files set it explicitly
for cross-compiling. Don't override preset values. But make sure
it's set for all x86 / x86_64 builds, not just Linux.

Also make sure -std=c++11 is set for Darwin builds, not all
submodules were getting it consistently before.

CMakeLists.txt

@@ -118,6 +118,7 @@ string(TOLOWER ${CMAKE_BUILD_TYPE} CMAKE_BUILD_TYPE_LOWER)
 # when ARCH is not set to an explicit identifier, cmake's builtin is used
 # to identify the target architecture, to direct logic in this cmake script.
 # Since ARCH is a cached variable, it will not be set on first cmake invocation.
+if (NOT ARCH_ID)
 if (NOT ARCH OR ARCH STREQUAL "" OR ARCH STREQUAL "native" OR ARCH STREQUAL "default")
   if(CMAKE_SYSTEM_PROCESSOR STREQUAL "")
     set(CMAKE_SYSTEM_PROCESSOR ${CMAKE_HOST_SYSTEM_PROCESSOR})
@@ -126,6 +127,7 @@ if (NOT ARCH OR ARCH STREQUAL "" OR ARCH STREQUAL "native" OR ARCH STREQUAL "def
 else()
   set(ARCH_ID "${ARCH}")
 endif()
+endif()
 string(TOLOWER "${ARCH_ID}" ARM_ID)
 string(SUBSTRING "${ARM_ID}" 0 3 ARM_TEST)
 if (ARM_TEST STREQUAL "arm")
@@ -414,7 +416,7 @@ if (CMAKE_SYSTEM_NAME MATCHES "(SunOS|Solaris)")
 endif ()
 
 if (APPLE AND NOT IOS)
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -march=x86-64 -fvisibility=default")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -march=x86-64 -fvisibility=default -std=c++11")
   if (NOT OpenSSL_DIR)
       EXECUTE_PROCESS(COMMAND brew --prefix openssl
         OUTPUT_VARIABLE OPENSSL_ROOT_DIR

contrib/depends/toolchain.cmake.in

@@ -104,12 +104,14 @@ if(ARCHITECTURE STREQUAL "riscv64")
     set(ARCH "rv64imafdc")
 endif()
 
-if(ARCHITECTURE STREQUAL "i686" AND CMAKE_SYSTEM_NAME STREQUAL "Linux")
-  SET(LINUX_32 ON)
+if(ARCHITECTURE STREQUAL "i686")
   SET(ARCH_ID "i386")
+  if(CMAKE_SYSTEM_NAME STREQUAL "Linux")
+    SET(LINUX_32 ON)
+  endif()
 endif()
 
-if(ARCHITECTURE STREQUAL "x86_64" AND CMAKE_SYSTEM_NAME STREQUAL "Linux")
+if(ARCHITECTURE STREQUAL "x86_64")
   SET(ARCH_ID "x86_64")
 endif()