Target "sniffer-test" links to item " -lpcap" which has leading or trailing
whitespace.  This is now an error according to policy CMP0004.

pcap-config --libs outputs a leading space

diff --git a/boreas/CMakeLists.txt b/boreas/CMakeLists.txt
index e2f86b2..d12d530 100644
--- a/boreas/CMakeLists.txt
+++ b/boreas/CMakeLists.txt
@@ -65,6 +65,7 @@ if (PCAP_CONFIG)
   execute_process (COMMAND pcap-config --cflags
     OUTPUT_VARIABLE PCAP_CFLAGS
     OUTPUT_STRIP_TRAILING_WHITESPACE)
+  string(STRIP "${PCAP_LDFLAGS}" PCAP_LDFLAGS)
 else (PCAP_CONFIG)
   message (STATUS "pcap-config not found, using defaults...")
   set (PCAP_LDFLAGS "-L/usr/lib -lpcap")