Adding -noprofile to CMakeLists for Windows

Summary:
In the off chance you have a `Microsoft.PowerShell_profile.ps1` profile the `execute_process` will load one's profile during running `cmake`, which will cause garbage output to be written to the `build_version.cc` file. If you add in a `-noprofile` flag, or you suppress output in your pshell profile, this is mitigated.
Closes https://github.com/facebook/rocksdb/pull/2168

Differential Revision: D4927003

Pulled By: siying

fbshipit-source-id: 83861752d6cf2627dd864eedd2acaa8aa8a6232e

CMakeLists.txt

@@ -66,8 +66,8 @@ else()
 endif()
 
 if(WIN32)
-  execute_process(COMMAND powershell -Command "Get-Date -format MM_dd_yyyy" OUTPUT_VARIABLE DATE)
-  execute_process(COMMAND powershell -Command "Get-Date -format HH:mm:ss" OUTPUT_VARIABLE TIME)
+  execute_process(COMMAND powershell -noprofile -Command "Get-Date -format MM_dd_yyyy" OUTPUT_VARIABLE DATE)
+  execute_process(COMMAND powershell -noprofile -Command "Get-Date -format HH:mm:ss" OUTPUT_VARIABLE TIME)
   string(REGEX REPLACE "(..)_(..)_..(..).*" "\\1/\\2/\\3" DATE "${DATE}")
   string(REGEX REPLACE "(..):(.....).*" " \\1:\\2" TIME "${TIME}")
   set(GIT_DATE_TIME "${DATE} ${TIME}")