v8: enhance signature mimatch message in getModuleFunction

[mathetake]

Signed-off-by: mathetake [email protected]

resolves #74

the following is an example message:

[source/extensions/common/wasm/wasm_vm.cc:29] Bad function signature for: proxy_on_vm_start, want: i32 -> void, but the module exports: i32 i32 -> void
[source/extensions/common/wasm/wasm_vm.cc:29] Bad function signature for: proxy_on_vm_start, want: i32 i32 -> void, but the module exports: i32 i32 -> void
[source/extensions/common/wasm/wasm_vm.cc:29] Bad function signature for: proxy_on_vm_start, want: i32 -> i32, but the module exports: i32 i32 -> i32
[source/extensions/common/wasm/wasm_vm.cc:29] Bad function signature for: proxy_on_vm_start, want: i32 i32 i32 -> i32, but the module exports: i32 i32 -> i32
[source/extensions/common/wasm/wasm_vm.cc:29] Bad function signature for: proxy_on_vm_start, want: i32 i32 i32 -> i32, but the module exports: i32 i32 -> i32
[source/extensions/common/wasm/wasm_vm.cc:29] Bad function signature for: proxy_on_vm_start, want: i32 i32 -> void, but the module exports: i32 i32 -> void
[source/extensions/common/wasm/wasm_vm.cc:29] Bad function signature for: proxy_on_vm_start, want: i32 i32 -> void, but the module exports: i32 i32 -> void
[source/extensions/common/wasm/wasm_vm.cc:29] Bad function signature for: proxy_on_vm_start, want: i32 i32 i32 -> i32, but the module exports: i32 i32 -> i32
[source/extensions/common/wasm/wasm_vm.cc:29] Bad function signature for: proxy_on_vm_start, want: i32 i32 i32 -> i32, but the module exports: i32 i32 -> i32
[source/extensions/common/wasm/wasm_vm.cc:29] Bad function signature for: proxy_on_vm_start, want: i32 i32 i32 i32 i32 -> void, but the module exports: i32 i32 -> void
[source/extensions/common/wasm/wasm_vm.cc:29] Bad function signature for: proxy_on_vm_start, want: i32 i32 i32 -> void, but the module exports: i32 i32 -> void
[source/extensions/common/wasm/wasm_vm.cc:29] Bad function signature for: proxy_on_vm_start, want: i32 i32 i32 -> void, but the module exports: i32 i32 -> void
[source/extensions/common/wasm/wasm_vm.cc:29] Bad function signature for: proxy_on_vm_start, want: i32 i32 i32 -> void, but the module exports: i32 i32 -> void
[source/extensions/common/wasm/wasm_vm.cc:29] Bad function signature for: proxy_on_vm_start, want: i32 i32 i32 -> void, but the module exports: i32 i32 -> void
[source/extensions/common/wasm/wasm_vm.cc:29] Bad function signature for: proxy_on_vm_start, want: i32 i32 -> void, but the module exports: i32 i32 -> void
[source/extensions/common/wasm/wasm_vm.cc:29] Bad function signature for: proxy_on_vm_start, want: i32 -> i32, but the module exports: i32 i32 -> i32
[source/extensions/common/wasm/wasm_vm.cc:29] Bad function signature for: proxy_on_vm_start, want: i32 -> void, but the module exports: i32 i32 -> void
[source/extensions/common/wasm/wasm_vm.cc:29] Bad function signature for: proxy_on_vm_start, want: i32 -> void, but the module exports: i32 i32 -> void
[source/extensions/common/wasm/wasm_vm.cc:29] Bad function signature for: proxy_on_vm_start, want: i32 i32 i32 -> void, but the module exports: i32 i32 -> void

[PiotrSikora]

LGTM sans nit.