Update and fix fuzzing instructions.

It's easier to put libFuzzer.a into the source directory than to install
it globally.

Change-Id: I4dc7b56f81c7aa0371475c68d23368b025186505
Reviewed-on: https://boringssl-review.googlesource.com/6461
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/CMakeLists.txt b/CMakeLists.txt
index c05e645..e07be54 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -88,6 +88,7 @@
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fsanitize=address -fsanitize-coverage=edge,indirect-calls")
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fsanitize=address -fsanitize-coverage=edge,indirect-calls")
   set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_C_FLAGS} -fsanitize=address")
+  link_directories(.)
 endif()
 
 add_definitions(-DBORINGSSL_IMPLEMENTATION)