Set CPP_ANSI_OPTS in Toolchain based makefile in Simulink Coder

When I build a Simulink model with the Toolchain approach, a makefile is automatically genereated. This makefile comprises a general header and a toolchain specific body. In the header there is defined a macro "CPP_ANSI_OPTS" that is later used in the toolchain specific part. What is written in the header cannot be influenced by the toolchain object. Rather, macros in the header can be set via BuildInfo.addMakeVars (e.g. in the PostCodeGenCommand hook). But when I set the CPP_ANSI_OPTS macro it is written once the way i defined it and then, at the end of the header, anothertime just like if was before ("-std=c++98 -pedantic -Wno-long-long -fwrapv") effecitvely overwriting my definition.

How can I influence, what is written in the makefile for the definition of CPP_ANSI_OPTS (and ANSI_OPTS)???