adopted a cleaner libevhtp pkgconfig patch

libevhtp/pkgconfig-librarypath.patch

@@ -1,20 +1,24 @@
-Author: Trolli Schmittlauch <t.schmittlauch@orlives.de>
-Date:   Sat Sep 14 20:32:03 2019 +0200
-
-    fix #143 by setting LIB_INSTALL_DIR CMake var
-
-diff --git a/CMakeLists.txt b/CMakeLists.txt
-index 481ddd0..833ddf9 100644
 --- a/CMakeLists.txt
 +++ b/CMakeLists.txt
-@@ -225,6 +225,10 @@ set(include_install_dir "include")
+@@ -14,6 +14,7 @@ include(CheckIncludeFiles)
+ include(CheckTypeSize)
+ include(CheckCCompilerFlag)
+ include(TestBigEndian)
++include(GNUInstallDirs)
 
- set(generated_dir "${CMAKE_CURRENT_BINARY_DIR}/generated")
+ check_function_exists(strndup HAVE_STRNDUP)
+ check_function_exists(strnlen HAVE_STRNLEN)
+diff --git a/evhtp.pc.in b/evhtp.pc.in
+index a7b351f..fbddc51 100644
+--- a/evhtp.pc.in
++++ b/evhtp.pc.in
+@@ -1,6 +1,7 @@
+ prefix=@CMAKE_INSTALL_PREFIX@
+-libdir=@LIB_INSTALL_DIR@
+-includedir=@INCLUDE_INSTALL_DIR@/evhtp
++exec_prefix=${prefix}
++libdir=${exec_prefix}/@CMAKE_INSTALL_LIBDIR@
++includedir=${prefix}/@CMAKE_INSTALL_INCLUDEDIR@/evhtp
 
-+if (NOT LIB_INSTALL_DIR)
-+       set (LIB_INSTALL_DIR "${CMAKE_INSTALL_PREFIX}/lib")
-+endif (NOT LIB_INSTALL_DIR)
-+
- # Configuration
- set(version_config "${generated_dir}/${PROJECT_NAME}ConfigVersion.cmake")
- set(project_config "${generated_dir}/${PROJECT_NAME}Config.cmake")
+ Name: libevhtp
+ Description: A more flexible replacement for libevent's httpd API