Corrected regression makefile

The makefile was pointing at the wrong directory, which somehow didn't
cause a CI failure, this corrects that. In doing so realised that the
test was slightly inaccurate, so resolved this issue as well.

Author: thk123

regression/Makefile

@@ -7,7 +7,7 @@ DIRS = ansi-c \
        goto-analyzer \
        goto-cc-cbmc \
        goto-cc-goto-analyzer \
-       goto-cc-goto-symex \
+       goto-cc-symex \
        goto-diff \
        goto-gcc \
        goto-instrument \

regression/goto-cc-symex/regenerate-entry-function/test.desc

@@ -1,7 +1,7 @@
 CORE
 main.c
 "--function fun --show-goto-functions"
-^\s*return.=fun\(x\);$
+fun\(x\);$
 ^EXIT=6$
 ^SIGNAL=0$
 --