Change chain.sh to allow for custom goto binary building

This changes the chain.sh (and adds a READFME.md to explain)
so that a test can be written that uses its own script to build
the goto binary.

Author: TGWDB

regression/goto-cc-goto-analyzer/README.md

@@ -0,0 +1,9 @@
+This subdirectory is for tests where goto-cc is used to produce
+a goto binary that is then passed to goto-analyzer. There is also
+the option to have a custom script to produce the goto binary
+should this require special handling or multiple steps. This
+script is run if the root name of the test file has a script with
+the same filename. For example, if the desc file specifies 
+test.c as the test file then the chain.sh script will check for
+the existence of test.sh and if test.sh exists then it will be used
+to build the goto binary (assumed to be test.gb).

regression/goto-cc-goto-analyzer/chain.sh

@@ -9,12 +9,17 @@ is_windows=$3
 options=${*:4:$#-4}
 name=${*:$#}
 name=${name%.c}
+buildgoto=${name}.sh
 
-if [[ "${is_windows}" == "true" ]]; then
-  "${goto_cc}" "${name}.c"
-  mv "${name}.exe" "${name}.gb"
+if test -f ${buildgoto}; then
+  ./${buildgoto} ${goto_cc} ${is_windows}
 else
-  "${goto_cc}" "${name}.c" -o "${name}.gb"
+  if [[ "${is_windows}" == "true" ]]; then
+    "${goto_cc}" "${name}.c"
+    mv "${name}.exe" "${name}.gb"
+  else
+    "${goto_cc}" "${name}.c" -o "${name}.gb"
+  fi
 fi
 
 "${goto_analyzer}" "${name}.gb" ${options}