Fix: 32-bit iOS builds failing due to targeting an iOS version that is too high

[nurupo]

iOS 10 is the maximum deployment target for 32-bit builds, yet we are targeting iOS 15. It looks like clang was updated and added a warning for this at some point, so our builds now fail, since we -Werror.

Snippet of the CI failure from TokTok/c-toxcore#3031:

2026-03-29T18:15:51.6473440Z configure:4287: checking whether the C compiler works
2026-03-29T18:15:51.6475210Z configure:4309: gcc -O3 -fPIC -miphoneos-version-min=15.0 -arch armv7 -isysroot /Applications/Xcode_15.4.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS17.5.sdk  -Dblake2b=sodium_blake2b -Dblake2b_final=sodium_blake2b_final -Dblake2b_init=sodium_blake2b_init -Dblake2b_init_key=sodium_blake2b_init_key -Dblake2b_init_param=sodium_blake2b_init_param -Dblake2b_update=sodium_blake2b_update  -miphoneos-version-min=15.0 -arch armv7 -isysroot /Applications/Xcode_15.4.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS17.5.sdk -fstack-protector conftest.c  >&5
2026-03-29T18:15:51.6477350Z clang: error: invalid iOS deployment version '-miphoneos-version-min=15.0', iOS 10 is the maximum deployment target for 32-bit targets [-Winvalid-ios-deployment-target]
2026-03-29T18:15:51.6477870Z configure:4313: $? = 1
2026-03-29T18:15:51.6478020Z configure:4354: result: no
2026-03-29T18:15:51.6478170Z configure: failed program was:
2026-03-29T18:15:51.6478320Z | /* confdefs.h */
2026-03-29T18:15:51.6478460Z | #define PACKAGE_NAME "libsodium"
2026-03-29T18:15:51.6478640Z | #define PACKAGE_TARNAME "libsodium"
2026-03-29T18:15:51.6478820Z | #define PACKAGE_VERSION "1.0.20"
2026-03-29T18:15:51.6479370Z | #define PACKAGE_STRING "libsodium 1.0.20"
2026-03-29T18:15:51.6479710Z | #define PACKAGE_BUGREPORT "https://github.com/jedisct1/libsodium/issues"
2026-03-29T18:15:51.6480030Z | #define PACKAGE_URL "https://libsodium.org"
2026-03-29T18:15:51.6480230Z | #define PACKAGE "libsodium"
2026-03-29T18:15:51.6480390Z | #define VERSION "1.0.20"
2026-03-29T18:15:51.6480570Z | /* end confdefs.h.  */
2026-03-29T18:15:51.6480710Z | 
2026-03-29T18:15:51.6480800Z | int
2026-03-29T18:15:51.6480910Z | main (void)
2026-03-29T18:15:51.6481020Z | {
2026-03-29T18:15:51.6481110Z | 
2026-03-29T18:15:51.6481200Z |   ;
2026-03-29T18:15:51.6481300Z |   return 0;
2026-03-29T18:15:51.6481410Z | }
2026-03-29T18:15:51.6481620Z configure:4359: error: in '/Users/runner/work/c-toxcore/c-toxcore/external/sodium':
2026-03-29T18:15:51.6481970Z configure:4361: error: C compiler cannot create executables
2026-03-29T18:15:51.6482210Z See 'config.log' for more details

While c-toxcore's other/deploy/ios.sh script does attempt to set the version to iOS 10:

https://github.com/TokTok/c-toxcore/blob/8ffeabe452938609c3516665db2f14785f259d30/other/deploy/ios.sh#L23

it does so too late in the script, as it sets it only for building toxcore, not the deps. The failure happens during the dep building, in the deps.sh call, which calls parse_arch function from TokTok/Dockerfiles's dockerfiles/qtox/build_utils.sh, where it's hardcoded to 15.0 via IOS_MINIMUM_SUPPORTED_VERSION=15.0:

dockerfiles/qtox/build_utils.sh

Line 36 in 0774716

IOS_MINIMUM_SUPPORTED_VERSION=15.0

This PR fixes builds failing due to the clang warning being triggered by setting the IOS_MINIMUM_SUPPORTED_VERSION to 10.0 for 32-bit iOS builds.

I have tested this change in the mentioned PR TokTok/c-toxcore#3031 with TokTok/c-toxcore@d18ee91 and it did indeed fix the failure.

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When trying to figure out why the c-toxcore iOS CI is failing, seeing it call into qtox scripts raised some eyebrows here. I thought it might be mistakenly calling the wrong scripts, since c-toxcore shouldn't have anything to do with qtox. Surprised there is no common deps directory of sorts.

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This change is