Alternate MSVC directory structure for PCRE

The MSVC build procedure is modified to recognize the
directory structure of "32 and 64-bit PCRE for Windows"
zip files downloadable from http://www.airesoft.co.uk

pcre
|-inc
| |-pcre.h
| |-pcreposix.h
|
|-lib
| |-pcre3.lib
| |-pcreposix3.lib
| |-x64
|   |-pcre3.lib
|   |-pcreposix3.lib
|
|-bin
  |-pcre3.dll
  |-pcreposix3.dll
  |-x64
    |-pcre3.dll
    |-pcreposix3.dll

The alternative structure for files downloaded from
http://gnuwin32.sourceforge.net/packages/pcre.htm
remains equally valid:

pcre
|-include
| |-pcre.h
| |-preposix.h
|
|-lib
| |-pcre.lib
| |-pcreposix.lib
|
|-bin
| |-pcre3.dll
| |-pcreposix3.dll
|
|-x64
  |-include
  | |-pcre.h
  | |-preposix.h
  |
  |-lib
  | |-pcre.lib
  | |-pcreposix.lib
  |
  |-bin
    |-pcre3.dll
    |-pcreposix3.dll