add -fPIC for all builds, even cross comiling to Windows from Linux, even non...

add -fPIC for all builds, even cross comiling to Windows from Linux, even non Debug and Release builds

Documentation/compiling/build-msw.txt

@@ -2,12 +2,13 @@ Introduction
 ------------
 
 This document details how to build KiCad from source on Windows. The current
-supported method of building KiCad on Windows systems is to use MinGW,
-either from MSYS or cross compiling from Linux. Visual Studio is not
-supported, and don't ask about it, it is not supported and will not be.
+supported method of building KiCad for Windows systems is to use the MinGW
+compiler, either from Windows or cross compiling from Linux. MSYS can be
+used on Windows to extend the range of subprojects that you can build, but
+is not needed to build KiCad itself.
 
-If you add or remove any of the KiCad build dependencies, please update this
-document.
+Visual Studio is not supported, and don't ask about it, it is not supported
+and will not be, ever.
 
 Install Build Tools
 -------------------