package/trinity: fix build with libexecinfo

Fix the following build failure raised on uclibc and musl since the
addition of libexecinfo package in commit
eea8ba446c10701a273432552108d80fb2224ef4:

/home/buildroot/autobuild/instance-2/output-1/host/opt/ext-toolchain/bin/../lib/gcc/mipsel-buildroot-linux-uclibc/10.3.0/../../../../mipsel-buildroot-linux-uclibc/bin/ld: debug.o: in function `__show_backtrace':
debug.c:(.text+0x10): undefined reference to `backtrace'

Fixes:
 - http://autobuild.buildroot.org/results/bf78e4be9b9d9ca7d32f922d72ea6cd39a78d3d8

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>

package/trinity/trinity.mk

@@ -11,16 +11,24 @@ TRINITY_LICENSE = GPL-2.0
 TRINITY_LICENSE_FILES = COPYING
 TRINITY_CPE_ID_VENDOR = trinity_project
 
+TRINITY_LDFLAGS = $(TARGET_LDFLAGS)
+
+ifeq ($(BR2_PACKAGE_LIBEXECINFO),y)
+TRINITY_DEPENDENCIES += libexecinfo
+TRINITY_LDFLAGS += -lexecinfo
+endif
+
 define TRINITY_CONFIGURE_CMDS
 	(cd $(@D); $(TARGET_CONFIGURE_OPTS) ./configure)
 endef
 
 define TRINITY_BUILD_CMDS
-	$(TARGET_CONFIGURE_OPTS) $(MAKE) -C $(@D)
+	$(TARGET_CONFIGURE_OPTS) $(MAKE) -C $(@D) LDFLAGS="$(TRINITY_LDFLAGS)"
 endef
 
 define TRINITY_INSTALL_TARGET_CMDS
-	$(TARGET_CONFIGURE_OPTS) $(MAKE) -C $(@D) DESTDIR=$(TARGET_DIR)/usr install
+	$(TARGET_CONFIGURE_OPTS) $(MAKE) -C $(@D) \
+		LDFLAGS="$(TRINITY_LDFLAGS)" DESTDIR=$(TARGET_DIR)/usr install
 endef
 
 # Install helper scripts