Update build configurations and reduce binary size

[julianrex]

mapbox-gl-native is simplifying the build configurations, to just Debug and Release (see mapbox/mapbox-gl-native#16083).

We need to do the same.

We can handle a "stripped" build (i.e. what is currently Release) as a packaging step, i.e. by default the new Release configuration will contain debug symbols.

At the same time we should consider #22

[julianrex]

Following on from #63:

Currently the release frameworks are NOT building with -flto or -Os, which has resulted in an increase in binary size. Here are some stats when building with various optimizations.

Build settings	framework size 1	dSYM size 2	arm64 slice size 3	arm64 no bitcode 4	arm64 stripped 5	__TEXT 6	__DATA	__OBJC	others
5.8.0	148065160	639619389	62868360	10439560	5162968	4800512	245760	0	116696
-Os -flto	85817300	344712182	38254548	4241364	4241364	3883008	245760	0	112596
-Oz -flto	72817804	325747720	31759500	3579020	3579020	3211264	245760	0	121996

Looking at compiling with -Os -flto, the framework size is brought back to original levels - though when compiling with -Oz the result is even more dramatic (~30% size reduction).

I would suggest that we update with -Os, then compare performance when compiling with -Oz ("outlining").

Symbols should be included the dSYM; though the size is much smaller compared with 5.8.0 so I suspect I made an error with the symbol handling. Need to check debugging, and call stacks on crashes.

These stats were built from the jrex/build-tests branch building with make iframework BUILDTYPE=Release BUILD_DOCS=false

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Notes:

1. Size of the Mapbox binary in the framework directory
2. Size of the binary in the Mapbo.framework.dSYM/Contents/Resources/DWARF/ directory
3. Size of the arm64 slice, extracted by: lipo Mapbox.framework/Mapbox -thin arm64 -output Mapbox-arm64
4. Size of binary generated by 3, with bitcode removed: xcrun bitcode_strip Mapbox-arm64 -r -o Mapbox-arm64-no-bitcode
5. Size of binary generated by 4, with symbols stripped: strip -Sx Mapbox-arm64-no-bitcode -o Mapbox-arm64-no-bitcode-stripped
6. Remaining columns are from running size on the above binary.

[julianrex]

Noting that we should consider a separate Github release artifact for the dSYM and bcsymbolmap files (see also mapbox/mapbox-gl-native-android#134).

[1ec5]

Noting that we should consider a separate Github release artifact for the dSYM and bcsymbolmap files (see also mapbox/mapbox-gl-native-android#134).

Note that Carthage (#143) expects the .dSYM to appear in the same .framework.zip archive as the executable.

[julianrex]

Note that Carthage (#143) expects the .dSYM to appear in the same .framework.zip archive as the executable.

Ok, so multiple packages 😭

[julianrex]

Have split out the update of Release and RelWithDebInfo configuration into a separate PR: mapbox/mapbox-gl-native#16460, so that existing build scripts/packaging is not changed.

I think it's still valid to consolidate configurations to just Release & Debug, so this ticket can be kept open for the time-being.