civetweb: use cmake

prometheus-cpp 1.0.0 depends on civetweb's cmake files being available:
    CMake Error at pull/CMakeLists.txt:11 (find_package):
      Could not find a package configuration file provided by "civetweb" with any
      of the following names:

        civetwebConfig.cmake
        civetweb-config.cmake

      Add the installation prefix of "civetweb" to CMAKE_PREFIX_PATH or set
      "civetweb_DIR" to a directory containing one of the above files.  If
      "civetweb" provides a separate development package or SDK, be sure it has
      been installed.

Cmake also properly handles setting the prefix, libdir, and includedir
paths, so that patch was dropped.

pkgs/development/libraries/civetweb/0001-allow-setting-paths-in-makefile.patch

@@ -1,33 +0,0 @@
-diff -u a/Makefile b/Makefile
---- a/Makefile	2020-12-27 18:48:53.934098765 +0100
-+++ b/Makefile	2020-12-27 18:50:44.022674117 +0100
-@@ -19,13 +19,13 @@
- # http://www.gnu.org/prep/standards/html_node/Directory-Variables.html
- PREFIX ?= /usr/local
- EXEC_PREFIX = $(PREFIX)
--BINDIR = $(EXEC_PREFIX)/bin
-+BINDIR ?= $(EXEC_PREFIX)/bin
- DATAROOTDIR = $(PREFIX)/share
- DOCDIR = $(DATAROOTDIR)/doc/$(CPROG)
- SYSCONFDIR ?= $(PREFIX)/etc
- HTMLDIR = $(DOCDIR)
--INCLUDEDIR = $(DESTDIR)$(PREFIX)/include
--LIBDIR = $(DESTDIR)$(EXEC_PREFIX)/lib
-+INCLUDEDIR ?= $(DESTDIR)$(PREFIX)/include
-+LIBDIR ?= $(DESTDIR)$(EXEC_PREFIX)/lib
- PID_FILE ?= /var/run/$(CPROG).pid
- 
- # build tools
-@@ -337,10 +337,10 @@
- 	install -m 755 $(CPROG) "$(BINDIR)/"
- 
- install-headers:
--	install -m 644 $(HEADERS) "$(INCLUDEDIR)"
-+	install -m 644 $(HEADERS) "$(INCLUDEDIR)/"
- 
- install-lib: lib$(CPROG).a
--	install -m 644 $< "$(LIBDIR)"
-+	install -m 644 $< "$(LIBDIR)/"
- 
- install-slib: lib$(CPROG).so
- 	$(eval version=$(shell grep -w "define CIVETWEB_VERSION" include/civetweb.h | sed 's|.*VERSION "\(.*\)"|\1|g'))

pkgs/development/libraries/civetweb/default.nix

@@ -1,5 +1,7 @@
-{ lib, stdenv
+{ lib
+, stdenv
 , fetchFromGitHub
+, cmake
 }:
 
 stdenv.mkDerivation rec {
@@ -13,33 +15,28 @@ stdenv.mkDerivation rec {
     sha256 = "sha256-Qh6BGPk7a01YzCeX42+Og9M+fjXRs7kzNUCyT4mYab4=";
   };
 
-  makeFlags = [
-    "WITH_CPP=1"
-    "PREFIX=${placeholder "out"}"
-    "LIBDIR=${placeholder "out"}/lib"
-    "INCLUDEDIR=${placeholder "dev"}/include"
-  ];
-
-  patches = [
-    ./0001-allow-setting-paths-in-makefile.patch
-  ];
+  outputs = [ "out" "dev" ];
 
   strictDeps = true;
 
-  outputs = [ "out" "dev" ];
-
-  installTargets = [
-    "install-headers"
-    "install-lib"
-    "install-slib"
-    "install"
+  nativeBuildInputs = [
+    cmake
   ];
 
-  preInstall = ''
-    mkdir -p $dev/include
-    mkdir -p $out/lib
+  # The existence of the "build" script causes `mkdir -p build` to fail:
+  #   mkdir: cannot create directory 'build': File exists
+  preConfigure = ''
+    rm build
   '';
 
+  cmakeFlags = [
+    "-DCIVETWEB_ENABLE_CXX=ON"
+    "-DBUILD_SHARED_LIBS=ON"
+
+    # The civetweb unit tests rely on downloading their fork of libcheck.
+    "-DCIVETWEB_BUILD_TESTING=OFF"
+  ];
+
   meta = {
     description = "Embedded C/C++ web server";
     homepage = "https://github.com/civetweb/civetweb";