correct root flags in AnalyzeCT.cpp compilation

The order in which the flags appear after g++ matters. The "compile" flags should go before the source file, the linking flags should go after, so you cannot combine them. Maybe the combined blurb was working with older versions of g++ and/or ROOT, but with g++ 9 and ROOT 6 it seems necessary to keep the compile flags and linking flags separate.

Author: djboersma

imaging/CT/readme.md

@@ -13,7 +13,7 @@ There are 2 runs. Each run performs during 90 seconds. The phantom turns around
 
 Compile the C++ file (in the classic directory) with the following command:
 
-`g++ -O3 `root-config -cflags -glibs` AnalyzeCT.cpp -o AnalyzeCT`
+```g++ -O3 `root-config --cflags` AnalyzeCT.cpp `root-config --glibs` -o AnalyzeCT```
 
 **Results**