tests/common/127: Fix test on MinGW 64-bit

Instead of hard-coding whether the symbol should be underscored,
detect it.

test cases/common/127 cpp and asm/meson.build

@@ -1,5 +1,6 @@
 project('c++ and assembly test', 'cpp')
 
+cpp = meson.get_compiler('cpp')
 cpu = host_machine.cpu_family()
 
 supported_cpus = ['arm', 'x86', 'x86_64']
@@ -8,6 +9,10 @@ if not supported_cpus.contains(cpu)
   error('MESON_SKIP_TEST unsupported cpu:' + cpu)
 endif
 
+if cpp.symbols_have_underscore_prefix()
+  add_project_arguments('-DMESON_TEST__UNDERSCORE_SYMBOL', language : 'cpp')
+endif
+
 sources = ['trivial.cc']
 # If the compiler cannot compile assembly, don't use it
 if meson.get_compiler('cpp').get_id() != 'msvc'

test cases/common/127 cpp and asm/symbol-underscore.h

@@ -1,4 +1,4 @@
-#if defined(__WIN32__) || defined(__APPLE__)
+#if defined(MESON_TEST__UNDERSCORE_SYMBOL)
 # define SYMBOL_NAME(name) _##name
 #else
 # define SYMBOL_NAME(name) name