Add cpp-httplib to oss-fuzz (#684)

* *Add server fuzzer target  and seed corpus
* Add fuzz_test option to Makefile

* Fix #685

* Try to fix Github actions on Ubuntu

* Added ReadTimeoutSSL test

* Comment out `-fsanitize=address`

* Rebase upstream changes

* remove address sanitizer temporarily

* Add separate Makefile for fuzzing

* 1. Remove special char from dictionary
2. Clean fuzzing/Makefile

* Use specific path to avoid accidently linking openssl version brought in by oss-fuzz

* remove addition of flags

* Refactor Makefile

* Add missing newline

* Add fuzztest to github workflow

* Fix

Co-authored-by: yhirose <yuji.hirose.bug@gmail.com>

test/fuzzing/corpus/1

@@ -0,0 +1 @@
+PUT /search/sample?a=12 HTTP/1.1

test/fuzzing/corpus/2

@@ -0,0 +1,5 @@
+GET /hello.htm HTTP/1.1
+User-Agent: Mozilla/4.0 (compatible; MSIE5.01; Windows NT)
+Accept-Language: en-us
+Accept-Encoding: gzip, deflate
+Connection: Keep-Alive