Replace libc printf with eyalroz/printf and add streaming status formatting.

[benvanik]

Integrates eyalroz/printf as a vendored dependency to replace all libc snprintf/vsnprintf calls across the runtime. This gives us a consistent, portable printf implementation across all platforms (including embedded and bare-metal targets) with no platform-specific quirks.

Beyond the drop-in replacement, this extends the status formatting API with streaming support:

• Add iree_status_format_to: callback-based streaming formatter that avoids contiguous buffers and pre-measurement passes. The callback returns bool for flow control, enabling early termination on buffer full or allocation failure.

• Add iree_string_builder_append_status: single-pass status-to-builder formatting via iree_status_format_to, resolving the status/string_builder dependency cycle that previously required a local copy in libhsa.c.

• Rewrite iree_status_fprint to stream directly to FILE* with zero heap allocation (previously required a contiguous buffer).

• Rewrite iree_status_to_string as single-pass using string builder instead of two-pass measure-then-format.

• Fix va_copy usage in status allocation: use C99 va_copy for the two-pass measure-then-format pattern instead of calling va_start twice on the same parameter (implementation-defined behavior).

• Convert Status::ToString (C++) and ApiStatusToString (Python bindings) from two-pass iree_status_format to single-pass iree_status_format_to.

• Replace HIP dynamic_symbols.c allocate-format-free pattern with direct iree_string_builder_append_status (eliminates intermediate heap allocation).

• RISC-V toolchain fix: strip debug info from libgcc.a during CMake configure. eyalroz/printf's long double support in %Lf/%Le compiles va_arg(args, long double) which on RISC-V (128-bit quad precision) generates references to __extenddftf2/__trunctfdf2 soft-float builtins. These are resolved from libgcc.a, but the GCC 12.2.0-compiled objects in that archive contain DWARF debug info with relocation types 60/61 (in .debug_rnglists and .debug_loclists sections) that LLD cannot parse. The pre-built RISC-V toolchain lacks compiler-rt builtins as an alternative, so we strip the debug metadata from libgcc.a at configure time using llvm-objcopy --strip-debug. This preserves all code and data sections and is idempotent. The strip runs inside the RISCV_TOOLCHAIN_ROOT guard so users with their own toolchains are unaffected. Verified locally with the same toolchain used in CI (toolchain_iree_manylinux_2_28_20231012).

ci-extra: all

[benvanik]

mac failures are disk space, linux arm64 is unrelated and have a pending a fix.