Fixes #12536 (#12568) [backport]

tests/compiler/tcmdlinecpuamd64.nim

@@ -0,0 +1,10 @@
+discard """
+  cmd: "nim $target $options --cpu:amd64 $file"
+  disabled: "32bit"
+"""
+
+import strutils
+
+static:
+  #cpu is set to "i386" in tcpuamd64.nim.cfg, but --cpu:amd64 in command line should override it.
+  doAssert cmpIgnoreCase(hostCPU, "amd64") == 0

tests/compiler/tcmdlinecpuamd64.nim.cfg

@@ -0,0 +1 @@
+cpu:i386

tests/compiler/tcmdlineoswin.nim

@@ -0,0 +1,14 @@
+discard """
+  cmd: "nim $target $options --os:windows $file"
+  disabled: "linux"
+  disabled: "bsd"
+  disabled: "macosx"
+  disabled: "unix"
+  disabled: "posix"
+"""
+
+import strutils
+
+static:
+  #os is set to "linux" in toswin.nim.cfg, but --os:windows in command line should override it.
+  doAssert cmpIgnoreCase(hostOS, "windows") == 0

tests/compiler/tcmdlineoswin.nim.cfg

@@ -0,0 +1 @@
+os:linux