Problem: CMake does not look for NSS using pkg-config

Solution: use pkg-config by default and FindPackage only as a
fallback

CMakeLists.txt

@@ -29,6 +29,8 @@ include(TestZMQVersion)
 include(ZMQSourceRunChecks)
 include(ZMQSupportMacros)
 
+find_package(PkgConfig)
+
 option(ENABLE_ASAN "Build with address sanitizer" OFF)
 if(ENABLE_ASAN)
   message(STATUS "Instrumenting with Address Sanitizer")
@@ -120,17 +122,23 @@ if (NOT DISABLE_WS)
   set(ZMQ_HAVE_WS 1)
 
   if (WITH_NSS)
-    find_package("NSS3")
+    pkg_check_modules(NSS3 "nss")
     if (NSS3_FOUND)
-      message(STATUS "Using NSS")
-      include_directories(${NSS3_INCLUDE_DIRS})
-      set(pkg_config_names_private "${pkg_config_names_private} nss3")
-      set(pkg_config_libs_private "${pkg_config_libs_private} -lnss3")
-      set(ZMQ_USE_NSS 1)
+      set(pkg_config_names_private "${pkg_config_names_private} nss")
     else()
-      message(FATAL_ERROR
-              "nss is not installed. Install it, then run CMake again")
+      find_package("NSS3")
+      if (NSS3_FOUND)
+        set(pkg_config_libs_private "${pkg_config_libs_private} -lnss3")
+      else()
+        message(FATAL_ERROR
+                "nss is not installed. Install it, then run CMake again")
+      endif()
     endif()
+    message(STATUS "Using NSS")
+    include_directories(${NSS3_INCLUDE_DIRS})
+    link_directories(${NSS3_LIBRARY_DIRS})
+    set(OPTIONAL_LIBRARIES ${NSS3_LIBRARIES})
+    set(ZMQ_USE_NSS 1)
   else()
     list(APPEND sources ${CMAKE_CURRENT_SOURCE_DIR}/external/sha1/sha1.c ${CMAKE_CURRENT_SOURCE_DIR}/external/sha1/sha1.h)
     message("Using builtin sha1")
@@ -139,7 +147,6 @@ if (NOT DISABLE_WS)
 endif()
 
 if(NOT MSVC)
-  find_package(PkgConfig)
   option(WITH_LIBBSD "Use libbsd instead of builtin strlcpy" ON)
   if (WITH_LIBBSD)
     pkg_check_modules(LIBBSD "libbsd")