Add dynamic build for curl and update tests

[vidyalakshmir]

Closes #100
Enable dynamic WebAssembly builds (LIND_DYLINK=1) for curl`

Shared libraries that git depends on:

• openssl (libssl.so and libcrypto.so)
• zlib (libz.so)
• libc

Summary

This PR updates the curl build pipeline to support cross-compiling as a WebAssembly Position Independent Executable (PIE). When LIND_DYLINK=1 is enabled, curl will be compiled to dynamically link its external dependencies (OpenSSL, zlib) at runtime via the lind-wasm environment, rather than statically linking them into the binary.

Technical Details

Building Autotools/Libtool projects for WebAssembly dynamic linking requires bypassing several traditional Linux/ELF assumptions. This PR implements the "Static Internal, Dynamic External" workaround.

1. Libtool / ELF Versioning Bypass

• By default, passing --enable-shared to curl's configure script causes Libtool to generate ELF version scripts (.ver), which WebAssembly's linker (wasm-ld) completely rejects.
• Fix: The script intentionally leaves --disable-shared --enable-static enabled for Libtool, but overrides the environment to force the compiler to use Position Independent Code (-fPIC). This causes curl's internal libraries (libcurl.la) to compile safely as .a archives containing PIC objects, which are then successfully linked into the final dynamic executable.

2. Linker Flag Splitting (LDFLAGS)

• autoconf feature tests frequently fail if they encounter undefined symbols too early.
• Fix: The script now uses two separate LDFLAGS arrays. LDFLAGS_CONFIGURE uses strict static linking rules so feature detection works cleanly. LDFLAGS_WASM (injected only during the make step) includes the necessary -Wl,-pie, --allow-undefined, and --unresolved-symbols=import-dynamic flags required to build the Wasm PIE.

3. CRT & Export Handling

• Includes required Lind-specific CRT objects (set_stack_pointer.o, crt1_shared.o).
• Modifies wasm-opt to support bulk memory and threads for dynamic environments.
• Runs add-export-tool immediately after optimization to expose __wasm_apply_tls_relocs, __wasm_apply_global_relocs, and __stack_pointer to the runtime host.

Test Runner Updates

• Runtime Preloading: Updated the test execution wrapper. When LIND_DYLINK=1, the test suite now runs lind_run with the necessary --preload env=... arguments. This resolves the unknown import errors by ensuring the Wasm runtime populates the env namespace with our shared dependencies before executing curl.cwasm.

How to Test

Test Static Path:

• make curl
• APP=curl make test

Test Dynamic Path:

• LIND_DYLINK=1 make curl
• LIND_DYLINK=1 APP=curl make test
  (This requires the updates from this PR which does dynamic compilation of libraries)