https://github.com/flann-lib/flann/pull/480

From 25eb56ec78472bd419a121c6905095a793cf8992 Mon Sep 17 00:00:00 2001
From: Mike Purvis <mpurvis@clearpath.ai>
Date: Fri, 9 Jul 2021 15:53:06 +0000
Subject: [PATCH] Use string(JOIN) to avoid semicolons in pc file.

---
 CMakeLists.txt    | 3 ++-
 cmake/flann.pc.in | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index f4b94d25..aabf93ac 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 2.6)
+cmake_minimum_required(VERSION 3.12)
 
 if(COMMAND cmake_policy)
     cmake_policy(SET CMP0003 NEW)
@@ -148,6 +148,7 @@ endif(BUILD_CUDA_LIB)
 
 find_package(PkgConfig REQUIRED)
 pkg_check_modules(LZ4 REQUIRED liblz4)
+string(JOIN " " LZ4_STATIC_LDFLAGS_STR ${LZ4_STATIC_LDFLAGS})
 
 #set the C/C++ include path to the "include" directory
 include_directories(BEFORE ${PROJECT_SOURCE_DIR}/src/cpp)
diff --git a/cmake/flann.pc.in b/cmake/flann.pc.in
index 07b8d649..1e7673ac 100644
--- a/cmake/flann.pc.in
+++ b/cmake/flann.pc.in
@@ -8,6 +8,6 @@ Name: @PROJECT_NAME@
 Description: @PKG_DESC@
 Version: @FLANN_VERSION@
 Requires: @PKG_EXTERNAL_DEPS@
-Libs: -L${libdir} @LZ4_STATIC_LDFLAGS@ -lflann -lflann_cpp
+Libs: -L${libdir} @LZ4_STATIC_LDFLAGS_STR@ -lflann -lflann_cpp
 Cflags: -I${includedir}