package/oatpp: disable tests

Fix the following build failure raised since the addition of the package
in commit d5bba26801b352f591451cf73e0b7509de0e6850:

[100%] Linking CXX executable oatppAllTests
/home/buildroot/instance-0/output-1/per-package/oatpp/host/opt/ext-toolchain/m68k-buildroot-uclinux-uclibc/bin/ld.real: cannot find -latomic: No such file or directory

Fixes: d5bba26801b352f591451cf73e0b7509de0e6850
 - http://autobuild.buildroot.org/results/1587b391baecdbb5a24a0c0b2c33d63cb71a2f7f

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
(cherry picked from commit 0af98ea2d889dd63bc6934236a625732ce28b059)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/oatpp/oatpp.mk

@@ -8,7 +8,7 @@ OATPP_VERSION = 1.3.0
 OATPP_SITE = $(call github,oatpp,oatpp,$(OATPP_VERSION))
 OATPP_LICENSE = Apache-2.0
 OATPP_LICENSE_FILES = LICENSE
-OATPP_CONF_OPTS = -DBUILD_SHARED_LIBS=OFF
+OATPP_CONF_OPTS = -DBUILD_SHARED_LIBS=OFF -DOATPP_BUILD_TESTS=OFF
 OATPP_INSTALL_STAGING = YES
 # Only builds a static lib and headers
 OATPP_INSTALL_TARGET = NO