RFR: Fix compilation errors due to missing spaces between string literal and macro

[Zhengyu Gu]

Fix build errors, e.g.
shenandoahHeapRegion.cpp:507:10: error: C++11 requires a space between 
string literal and macro [-Werror=c++11-compat]

Webrev: 
http://cr.openjdk.java.net/~zgu/shenandoah/string_literal/webrev.00/index.html

Test:

   Built on Linux 64 (fastdebug  and release)

Thanks,

-Zhengyu