[Dev] Clean up deprecation warnings from vault_darwin.c

[ycombinator]

As a developer of Elastic Agent, whenever I run any command on Mac OS that involves running go build, e.g. mage -l, the following deprecation warnings are shown:

# github.com/elastic/elastic-agent/internal/pkg/agent/vault
vault_darwin.c:65:23: warning: 'SecKeychainSetPreferenceDomain' is deprecated: first deprecated in macOS 10.10 - SecKeychain is deprecated [-Wdeprecated-declarations]
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Frameworks/Security.framework/Headers/SecKeychain.h:446:10: note: 'SecKeychainSetPreferenceDomain' has been explicitly marked deprecated here
vault_darwin.c:67:18: warning: 'SecKeychainCopyDomainDefault' is deprecated: first deprecated in macOS 10.10 - SecKeychain is deprecated [-Wdeprecated-declarations]
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Frameworks/Security.framework/Headers/SecKeychain.h:430:10: note: 'SecKeychainCopyDomainDefault' has been explicitly marked deprecated here
vault_darwin.c:77:23: warning: 'SecKeychainFindGenericPassword' is deprecated: first deprecated in macOS 10.10 - SecKeychain is deprecated [-Wdeprecated-declarations]
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Frameworks/Security.framework/Headers/SecKeychain.h:628:10: note: 'SecKeychainFindGenericPassword' has been explicitly marked deprecated here
vault_darwin.c:85:22: warning: 'SecKeychainItemModifyAttributesAndData' is deprecated: first deprecated in macOS 10.10 - SecKeychain is deprecated [-Wdeprecated-declarations]
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Frameworks/Security.framework/Headers/SecKeychainItem.h:165:10: note: 'SecKeychainItemModifyAttributesAndData' has been explicitly marked deprecated here
vault_darwin.c:90:9: warning: 'SecKeychainItemFreeContent' is deprecated: first deprecated in macOS 10.10 - SecKeychain is deprecated [-Wdeprecated-declarations]
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Frameworks/Security.framework/Headers/SecKeychainItem.h:220:10: note: 'SecKeychainItemFreeContent' has been explicitly marked deprecated here
vault_darwin.c:115:22: warning: 'SecKeychainItemCreateFromContent' is deprecated: first deprecated in macOS 10.10 - SecKeychain is deprecated [-Wdeprecated-declarations]
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Frameworks/Security.framework/Headers/SecKeychainItem.h:181:10: note: 'SecKeychainItemCreateFromContent' has been explicitly marked deprecated here
vault_darwin.c:146:23: warning: 'SecKeychainFindGenericPassword' is deprecated: first deprecated in macOS 10.10 - SecKeychain is deprecated [-Wdeprecated-declarations]
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Frameworks/Security.framework/Headers/SecKeychain.h:628:10: note: 'SecKeychainFindGenericPassword' has been explicitly marked deprecated here
vault_darwin.c:159:9: warning: 'SecKeychainItemFreeContent' is deprecated: first deprecated in macOS 10.10 - SecKeychain is deprecated [-Wdeprecated-declarations]
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Frameworks/Security.framework/Headers/SecKeychainItem.h:220:10: note: 'SecKeychainItemFreeContent' has been explicitly marked deprecated here
vault_darwin.c:174:23: warning: 'SecKeychainFindGenericPassword' is deprecated: first deprecated in macOS 10.10 - SecKeychain is deprecated [-Wdeprecated-declarations]
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Frameworks/Security.framework/Headers/SecKeychain.h:628:10: note: 'SecKeychainFindGenericPassword' has been explicitly marked deprecated here
vault_darwin.c:191:23: warning: 'SecKeychainFindGenericPassword' is deprecated: first deprecated in macOS 10.10 - SecKeychain is deprecated [-Wdeprecated-declarations]
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Frameworks/Security.framework/Headers/SecKeychain.h:628:10: note: 'SecKeychainFindGenericPassword' has been explicitly marked deprecated here
vault_darwin.c:198:18: warning: 'SecKeychainItemDelete' is deprecated: first deprecated in macOS 10.10 - SecKeychain is deprecated [-Wdeprecated-declarations]
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Frameworks/Security.framework/Headers/SecKeychainItem.h:257:10: note: 'SecKeychainItemDelete' has been explicitly marked deprecated here

It would be nice to have these cleaned up so the actual output of the command is seen right after the command is executed.

[ycombinator]

@aleksmaus Looks like the APIs mentioned in the deprecation warnings were first used in #398. Is this cleanup something you could help with?

[aleksmaus]

@aleksmaus Looks like the APIs mentioned in the deprecation warnings were first used in #398. Is this cleanup something you could help with?

Sure can take a look.