We need -lpthread for the pthread example

docs/examples/Makefile.example

@@ -30,6 +30,7 @@ LDFLAGS = -L/home/dast/lib -L/usr/local/ssl/lib
 # We need -lsocket and -lnsl when on Solaris
 # We need -lssl and -lcrypto when using libcurl with SSL support
 # We need -ldl for dlopen() if that is in libdl
+# We need -lpthread for the pthread example
 LIBS = -lcurl -lsocket -lnsl -lssl -lcrypto -dl
 
 # Link the target with all objects and libraries