contrib: Fix a bug in the libressl rules.mak file.

This fixes the spurious "sh: call: command not found" error that would
be printed on any 'make' invocation.  The source of the error was
pinpointed using strace.

Change-Id: Iea866e23a5b98bba0d108cf5f7b1723052fe81a7

contrib/src/libressl/rules.mak

@@ -25,7 +25,7 @@ LIBRESSL_URL := https://github.com/libressl-portable/portable/archive/$(LIBRESSL
 OPENBSD_URL := https://github.com/libressl-portable/openbsd/archive/$(OPENBSD_VERSION).tar.gz
 
 # Check if openssl or libressl is already present on the system
-ifeq ($(call need_pkg,"openssl >= 1.0.0" || call need_pkg,"libressl >= 1.0.0"),)
+ifeq ($(or $(call need_pkg,"openssl >= 1.0.0"),$(call need_pkg,"libressl >= 1.0.0")),)
 PKGS_FOUND += libressl
 endif