build: Use default RandomizedBaseAddress directive in VC9+ project files

Visual Studio 2008 introduced support for the address space layout
randomization (ASLR) feature of Windows Vista. However, upgrading the
VC8 project files to VC9 and above disabled this feature.

Removed the RandomizedBaseAddress directive to enabled the default
setting (/DYNAMICBASE). Note: This doesn't appear to have any negative
impact when compiled and ran on Windows XP.