openh264's build/ should not be removed

• Buildroot commit sha1: 2024.08-1338-gd74a5a218f with my patch
• Distribution of the build machine: Ubuntu VERSION="24.04.1 LTS (Noble Numbat)

I want to build openh264 using meson. To do it I have applied my patch. You can use my repo to reproduce...

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What happens

I can't build openh264 with error

make[2]: *** No rule to make target 'build/platform-linux.mk'.  Stop.

I know why, let's get libopenh264.log file

make libopenh264-dirclean -C buildroot
make libopenh264-rebuild -C buildroot 2>&1 |tee libopenh264.log

look at libopenh264.log:

gzip -d -c /home/a/mycode/buildroot_x86_non-simd_openh264_meson/buildroot/dl/libopenh264/libopenh264-2.4.1.tar.gz | tar --strip-components=1 -C /home/a/mycode/buildroot_x86_non-simd_openh264_meson/buildroot/output/build/libopenh264-2.4.1   -xf -
[7m>>> libopenh264 2.4.1 Patching[27m
[7m>>> libopenh264 2.4.1 Configuring[27m
rm -rf /home/a/mycode/buildroot_x86_non-simd_openh264_meson/buildroot/output/build/libopenh264-2.4.1//build
mkdir -p /home/a/mycode/buildroot_x86_non-simd_openh264_meson/buildroot/output/build/libopenh264-2.4.1//build

After unarchiving build/ folder was removed! This is mistake because build/ contains important files. This is not just empty folder for building... We shouldn't remove it... I think fix should be somewhere here and here... I suggest use --clearcache changes option instead of rm -rf, see my patch "[PATCH 1/1] package/pkg-meson: use --clearcache instead of rm -rf" in email...

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What was expected

Successfully build libopenh264 by meson.