Refine LGTM configuration (#99)

Author: dan4thewin

.lgtm.yml

@@ -1,5 +1,25 @@
+path_classifiers:
+  library:
+    - exclude: /
 extraction:
   cpp:
     index:
       build_command:
-        - 'CFLAGS=-Iinclude -ansi -Wall -Wextra -Wpedantic -Werror' make -C source core_json.o
+        - export 'CFLAGS=-Iinclude -ansi -Wall -Wextra -Wpedantic -Werror'
+        - make -C source core_json.o
+
+  csharp:
+    after_prepare:
+      - false
+  go:
+    after_prepare:
+      - false
+  java:
+    after_prepare:
+      - false
+  javascript:
+    after_prepare:
+      - false
+  python:
+    after_prepare:
+      - false