Makefile: disable always building statically.

Signed-off-by:  "Olivier Singla" <olivier.singla@gmail.com>

--- shellinabox-2.19/Makefile.am.orig	2016-07-03 20:46:42.655784211 -0400
+++ shellinabox-2.19/Makefile.am	2016-07-03 20:46:50.582801842 -0400
@@ -126,7 +126,7 @@
 
 shellinaboxd_LDADD   = liblogging.la                                          \
                        libhttp.la
-shellinaboxd_LDFLAGS = -static
+shellinaboxd_LDFLAGS =
 ## Added this for compatibility with older versions of autoconf/automake
 docdir               = ${datadir}/doc/${PACKAGE}