[source] tools: cmake: use pkg-config to discover libcrypto linker flags

[LEDE Commits]

jow pushed a commit to source.git, branch master:
https://git.lede-project.org/f9b253147a27d4fbe2558624fc68323ff9de2f22

commit f9b253147a27d4fbe2558624fc68323ff9de2f22
Author: Jo-Philipp Wich <jo at mein.io>
AuthorDate: Thu Jan 5 14:16:57 2017 +0100

    tools: cmake: use pkg-config to discover libcrypto linker flags
    
    LibreSSL's libcrypto.so has an indirect dependency to librt for clock_gettime()
    on Linux.
    
    Use pkg-config to portably discover the required linker flags.
    
    Signed-off-by: Jo-Philipp Wich <jo at mein.io>
---
 tools/cmake/Makefile | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/cmake/Makefile b/tools/cmake/Makefile
index 9545e12..13390ab 100644
--- a/tools/cmake/Makefile
+++ b/tools/cmake/Makefile
@@ -21,7 +21,8 @@ include $(INCLUDE_DIR)/host-build.mk
 
 HOST_CONFIGURE_CMD := MAKEFLAGS="$(HOST_JOBS)" $(BASH) ./configure
 
-HOST_CONFIGURE_VARS :=
+HOST_CONFIGURE_VARS := \
+	LDFLAGS="$$$$(pkg-config --static --libs libcrypto)"
 
 HOST_CONFIGURE_ARGS := \
 	--prefix=$(STAGING_DIR_HOST)