How to fix compiler errors during MSVC build of OpenSSL

See also:

• Software notes
  
• Hardware notes
  

Problem: When building OpenSSL using Microsoft Visual Studio (MS Visual C++) by running

nmake -f ms\ntdll.mak

.\crypto\cversion.c(105) : error C2220: warning treated as error - no 'object' file generated
.\crypto\cversion.c(105) : warning C4129: 'o' : unrecognized character escape sequence

NMAKE : fatal error U1077: 'cl' : return code '0x2'

Stop.

Solution:
When you run the perl script to configure the build system for MS VC, make sure to specify Unix-style forward slashes (c:/blah/blah) instead of DOS-style backslashes (c:\blah\blah) when specifying the folder where you want OpenSSL installed.