libraries: add cpp-httplib

repo: https://github.com/yhirose/cpp-httplib

Author: wfrisch

.gitmodules

@@ -273,3 +273,6 @@
 [submodule "libraries/tz"]
 	path = libraries/tz
 	url = https://github.com/eggert/tz
+[submodule "libraries/cpp-httplib"]
+	path = libraries/cpp-httplib
+	url = https://github.com/yhirose/cpp-httplib

config.py

@@ -177,6 +177,9 @@ def sparse_paths(self):
         "unzcrash.c",
         "mk251.c",
         ]),
+    Library('cpp-httplib', [
+        "httplib.h",
+        ]),
     Library('curl', [
         "lib/url.c",
         "lib/urldata.h",