RFR: JDK-8148955: libjimage.so compiled with wrong flags

[Erik Joelsson]

The library libjimage.so consists of C++ source files, but is currently 
setup to compile using CFLAGS_JDKLIB instead of CXXFLAGS_JDKLIB. On 
Solaris, these variables contain quite a few differences due to the 
compilers taking very different arguments. This makes the build process 
very noisy in the build log.

When correcting the flags, the proper warnings were also enabled. I took 
the liberty of fixing the warning complaining about the variable "i" 
hiding a variable in the outer scope.

Bug: https://bugs.openjdk.java.net/browse/JDK-8148955
Webrev: http://cr.openjdk.java.net/~erikj/8148955/webrev.jdk.01/

/Erik