curl: switch to cmake unity with 8.5.0 [ci skip]

Switch from `curl-gnumake.sh` to `curl-cmake.sh` with upcoming curl
release v8.5.0.

cmake builds are now _faster_ for Windows builds than raw gnumake
(aka `Makefile.mk`). They also use 'unity' mode, which makes builds
run fast with the side-effect of also creating potentially more
efficient binaries by allowing better compiler optimizations.

This also makes curl-for-win use the same build system for all target
platforms (`Makefile.mk` is not available for *nix platforms).

Initially on 2022-07-04 cmake was 25% slower than gnumake. By
2022-09-26 this reduced to 20%, by 2023-07-29 to 18% and after the
latest round of updates gnumake came out 7% slower than cmake.
This is for Windows, for a triple x64, arm64 and x86 build. In
absolute times this is 27m22s for cmake and 29m11s for gnumake.

(FWIW autotools builds are 52% slower than cmake unity builds now.)

Making cmake builds fast was a multi-year effort with these major steps:

1. add support for cmake builds in curl-for-win.
   420e73c
2. bring it in-line with gnumake and autotools builds and tidy-up
   as much as possible. Scattered to a many commits.
3. delete a whole bunch of unused feature detections.
   curl/curl@4d73854
   curl/curl#9044
   (and a lot more smaller commits)
4. speed up picky warning option initialization by avoiding brute-force
   all options. (first in libssh2, then in curl, then applied also
   ngtcp2, nghttp3, nghttp2)
   curl/curl@9c543de
   curl/curl#10973
5. implement single build run for shared and static libcurl + tool
   (first in libssh2)
   curl/curl@1199308
   curl/curl#11505
   53dcd49
6. implement single build pass for shared and static libcurl
   (for Windows initially)
   curl/curl@2ebc74c
   curl/curl#11546
7. extend above to non-Windows (e.g. macOS)
   curl/curl@fc9bfb1
   curl/curl#11627
   bafa77d (mac)
   1b27304 (linux)
8. implement unity builds: single compiler invocation for libcurl + tool
   curl/curl@3f8fc25
   curl/curl#11095
   curl/curl@f42a279
   curl/curl#11928
   67d7fd3
9. speed up 4x the cmake initialization phase (for Windows)
   curl/curl@2100d9f
   curl/curl#12044
10. speed up cmake initialization even more by pre-filling
   detection results for our well-known mingw-w64 environments.
   74dd967
   5a43c61

+1: speed up autotools initialization by mitigating a brute-force
   feature detection on Windows. This reduced total build times
   by 5 minutes at the time, for the 3 Windows targets in total.
   curl/curl@6adcff6
   curl/curl#9591

Also update build times for cmake-unity and gnumake, based on runs:
cmake-unity: https://ci.appveyor.com/project/curlorg/curl-for-win/builds/48357875
gnumake: https://ci.appveyor.com/project/curlorg/curl-for-win/builds/48358005

Author: vszakats

_build.sh

@@ -81,9 +81,6 @@ set -o xtrace -o errexit -o nounset; [ -n "${BASH:-}${ZSH_NAME:-}" ] && set -o p
 #     curl-linux-musl / curl-mac / curl-x64.exe / curl-x86.exe / curl-a64.exe
 #     (or similar)
 #   - change default TLS to BoringSSL (with OPENSSL_SMALL?) or LibreSSL?
-#   - win: switch to curl-cmake.sh (from curl-gnumake.sh) to use the same build
-#     method for all target platforms. This will have a 20% build-performance
-#     hit for curl builds.
 #   - switch to libssh2-cmake.sh by default? (both for libssh2.sh and as
 #     non-Windows fallback in libssh2-gnumake.sh). Consider enabling unity mode.
 #     The advantage of autotools here is that it allows to exercise the
@@ -117,10 +114,10 @@ set -o xtrace -o errexit -o nounset; [ -n "${BASH:-}${ZSH_NAME:-}" ] && set -o p
 #   - https://sourceware.org/git/binutils-gdb.git
 #   - https://github.com/netwide-assembler/nasm
 
-# Build times (2023-07-29):
-#   - gnumake:                   33 min 18 sec   1998s   100%
-#   - cmake with dual patch:     39 min 12 sec   2352s   118%   100%
-#   - autotools:                 41 min 40 sec   2500s   125%   106%
+# Build times for windows (2023-10-25):
+#   - cmake-unity:  27 min 22 sec   1642s   100%
+#   - gnumake:      29 min 11 sec   1751s   107%   100%
+#   - autotools:    41 min 40 sec   2500s   152%   143%
 
 # Supported build tools:
 #
@@ -145,7 +142,7 @@ set -o xtrace -o errexit -o nounset; [ -n "${BASH:-}${ZSH_NAME:-}" ] && set -o p
 #   wolfssh          autotools
 #   libssh           cmake
 #   libssh2          autotools, gnumake [windows-only], cmake-unity
-#   curl             gnumake [windows-only], cmake-unity [non-windows default], autotools
+#   curl             cmake-unity [non-windows default], autotools, gnumake [windows-only]
 
 cd "$(dirname "$0")"
 

curl-gnumake.sh

@@ -7,7 +7,7 @@
 set -o xtrace -o errexit -o nounset; [ -n "${BASH:-}${ZSH_NAME:-}" ] && set -o pipefail
 
 # Unixy platforms require the configure phase, thus cannot build with pure GNU Make.
-if [ "${_OS}" != 'win' ]; then
+if [ "${_OS}" != 'win' ] || [ "${CURL_VER_}" != '8.4.0' ]; then
   ./curl-cmake.sh "$@"
   exit
 fi