Update the toolchain and Static Linux SDK (#287)

The PR updates the toolchain and Static Linux SDK. This resolves the
compilation errors below:

```
Building vminitd and vmexec...
Building for debugging...
<unknown>:0: error: stack nearly exhausted; compilation time may suffer, and crashes due to stack overflow are likely
<module-includes>:1:10: note: in file included from <module-includes>:1:
1 | #include "SwiftMusl.h"
  |          `- note: in file included from <module-includes>:1:
2 | 

/Users/Dmitry/Library/org.swift.swiftpm/swift-sdks/swift-6.2-DEVELOPMENT-SNAPSHOT-2025-06-25-a_static-linux-0.0.1.artifactbundle/swift-6.2-DEVELOPMENT-SNAPSHOT-2025-06-25-a_static-linux-0.0.1/swift-linux-musl/musl-1.2.5.sdk/aarch64/usr/lib/swift_static/linux-static/aarch64/SwiftMusl.h:135:10: error: could not build module 'sys_stropts'
133 | #include <sys/signalfd.h>
134 | #include <sys/statfs.h>
135 | #include <sys/stropts.h>
    |          `- error: could not build module 'sys_stropts'
136 | #include <sys/swap.h>
137 | #include <sys/syscall.h>

<unknown>:0: error: stack nearly exhausted; compilation time may suffer, and crashes due to stack overflow are likely
<unknown>:0: error: could not build C module 'SwiftMusl'
<unknown>:0: error: stack nearly exhausted; compilation time may suffer, and crashes due to stack overflow are likely
<module-includes>:1:10: note: in file included from <module-includes>:1:
1 | #include "SwiftMusl.h"
  |          `- note: in file included from <module-includes>:1:
2 | 

/Users/Dmitry/Library/org.swift.swiftpm/swift-sdks/swift-6.2-DEVELOPMENT-SNAPSHOT-2025-06-25-a_static-linux-0.0.1.artifactbundle/swift-6.2-DEVELOPMENT-SNAPSHOT-2025-06-25-a_static-linux-0.0.1/swift-linux-musl/musl-1.2.5.sdk/aarch64/usr/lib/swift_static/linux-static/aarch64/SwiftMusl.h:135:10: error: could not build module 'sys_stropts'
133 | #include <sys/signalfd.h>
134 | #include <sys/statfs.h>
135 | #include <sys/stropts.h>
    |          `- error: could not build module 'sys_stropts'
136 | #include <sys/swap.h>
137 | #include <sys/syscall.h>

<unknown>:0: error: stack nearly exhausted; compilation time may suffer, and crashes due to stack overflow are likely
<unknown>:0: error: could not build C module 'SwiftMusl'
[719/1348] Compiling x_all.cc
make[1]: *** [all] Error 1
make: *** [vminitd] Error 2
```

To update:

- Run `make cross-prep`
- List the installed Static Linux SDKs using `swift sdk list`
- Remove the old Static Linux SDKs using `swift sdk remove <SDK>`

Optionally:

- List the installed toolchains using `swiftly list`
- Uninstalled the old toolchains using `swiftly uninstall <TOOLCHAIN>`

Author: dkovba

.swift-version

@@ -1 +1 @@
-6.2-snapshot-2025-06-25
+6.2-snapshot-2025-09-06

vminitd/Makefile

@@ -17,8 +17,8 @@ WARNINGS_AS_ERRORS ?= true
 SWIFT_WARNING_CONFIG = $(if $(filter-out false,$(WARNINGS_AS_ERRORS)),-Xswiftc -warnings-as-errors)
 SWIFT_CONFIGURATION := --swift-sdk aarch64-swift-linux-musl $(SWIFT_WARNING_CONFIG)
 
-SWIFT_VERSION = 6.2-snapshot-2025-06-25
-SWIFT_SDK_URL = https://download.swift.org/swift-6.2-branch/static-sdk/swift-6.2-DEVELOPMENT-SNAPSHOT-2025-06-25-a/swift-6.2-DEVELOPMENT-SNAPSHOT-2025-06-25-a_static-linux-0.0.1.artifactbundle.tar.gz
+SWIFT_VERSION = 6.2-snapshot-2025-09-06
+SWIFT_SDK_URL = https://download.swift.org/swift-6.2-branch/static-sdk/swift-6.2-DEVELOPMENT-SNAPSHOT-2025-09-06-a/swift-6.2-DEVELOPMENT-SNAPSHOT-2025-09-06-a_static-linux-0.0.1.artifactbundle.tar.gz
 SWIFT_SDK_PATH = /tmp/$(notdir $(SWIFT_SDK_URL))
 
 SWIFTLY_URL := https://download.swift.org/swiftly/darwin/swiftly.pkg