Compiler warnings on clang++ for archs armv7 and armv7s

[jnavarrom]

Do you think we can take care of these warning?

clang++ -DNDEBUG -g2 -O3 -fPIC -pipe -Wall -arch armv7 -isysroot "/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS12.1.sdk" -stdlib=libc++ -ffunction-sections -fdata-sections -c scrypt.cpp
scrypt.cpp:167:24: warning: result of comparison of constant 137438953440 with expression of type 'size_t' (aka 'unsigned long') is always false [-Wtautological-constant-out-of-range-compare]
        if (derivedLen > maxLen) {
            ~~~~~~~~~~ ^ ~~~~~~

clang++ -DNDEBUG -g2 -O3 -fPIC -pipe -Wall -miphoneos-version-min=6 -arch armv7s -isysroot "/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS12.1.sdk" -stdlib=libc++ -ffunction-sections -fdata-sections -c scrypt.cpp
scrypt.cpp:167:24: warning: result of comparison of constant 137438953440 with expression of type 'size_t' (aka 'unsigned long') is always false [-Wtautological-constant-out-of-range-compare]
        if (derivedLen > maxLen) {
            ~~~~~~~~~~ ^ ~~~~~~

[noloader]

Yeah, these are annoying at times. I believe -Wno-tautological-compare does the trick for Clang. I think it got removed a while ago from the flags set by setenv-ios.sh.

Let me add it to the sources.

[noloader]

Cleared at Commit 22a25c0e84dd.