Add missing eval to prefix command

This was missing causing bash to run the command with quotes incorrectly
on Ubuntu.
This was originally missed as the script skips the checks if no cpp
files are touched

buildconfig/Jenkins/cppcheck.sh

@@ -32,7 +32,7 @@ if [ $(command -v scl) ]; then
     SCL_ENABLE="scl enable devtoolset-7"
 else
     CMAKE_EXE=cmake
-    SCL_ENABLE=""
+    SCL_ENABLE="eval"
 fi
 $SCL_ENABLE "$CMAKE_EXE --version"