build: Temporarily remove confusing and brittle -fdebug-prefix-map

contrib/guix/libexec/build.sh

@@ -211,6 +211,7 @@ CONFIGFLAGS="-DREDUCE_EXPORTS=ON -DBUILD_BENCH=OFF -DBUILD_GUI_TESTS=OFF -DBUILD
 # CFLAGS
 HOST_CFLAGS="-O2 -g"
 HOST_CFLAGS+=$(find /gnu/store -maxdepth 1 -mindepth 1 -type d -exec echo -n " -ffile-prefix-map={}=/usr" \;)
+HOST_CFLAGS+=" -fdebug-prefix-map=${DISTSRC}/src=."
 case "$HOST" in
     *mingw*)  HOST_CFLAGS+=" -fno-ident" ;;
     *darwin*) unset HOST_CFLAGS ;;