Do not duplicate shared library when installing, use symlink instead

Regression was added in commit cae277e4377acc90ef787d09ed0d82968bbe809a
diff --git a/Makefile.in b/Makefile.in
index 002d25d..1a40de2 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -260,7 +260,7 @@
 	if [ -f libsrtp.dll.a ]; then cp libsrtp.dll.a $(DESTDIR)$(libdir)/; fi
 	if [ -f libsrtp.$(SHAREDLIBSUFFIX) ]; then \
 		cp libsrtp.$(SHAREDLIBSUFFIX) $(DESTDIR)$(SHAREDLIB_DIR)/; \
-		cp libsrtp.$(SHAREDLIBSUFFIXNOVER) $(DESTDIR)$(SHAREDLIB_DIR)/; \
+		ln -sfn libsrtp.$(SHAREDLIBSUFFIX) $(DESTDIR)$(SHAREDLIB_DIR)/libsrtp.$(SHAREDLIBSUFFIXNOVER); \
 	fi
 	if [ "$(pkgconfig_DATA)" != "" ]; then \
 		$(INSTALL) -d $(DESTDIR)$(pkgconfigdir); \