Travis: codecov: use -f with luacov output (#2563)

- do not use `-c` to remove discovered file
- configure path for luacov reportfile to also reside in build directory

.luacov

@@ -10,6 +10,7 @@ end
 
 return {
     statsfile = build .. "/luacov.stats.out",
+    reportfile = build .. "/luacov.report.out",
 
     include = {
         escape_pattern(source) .. "/.+",

.travis.yml

@@ -116,8 +116,8 @@ install:
       if [ "$DO_COVERAGE" = "codecov" ]; then
         test -f build/luacov.stats.out || { echo 'build/luacov.stats.out does not exist.'; return 1; }
         luacov || return 1
-        travis_retry bash /tmp/codecov-bash -X gcov -X coveragepy -c -F "$1,${LUANAME//./}" || return 1
-        rm build/luacov.stats.out
+        travis_retry bash /tmp/codecov-bash -f build/luacov.report.out -X gcov -X coveragepy -F "$1,${LUANAME//./}" || return 1
+        rm build/luacov.report.out build/luacov.stats.out
       fi
       return 0
     }