test/64bit_child: determine bitness at compile-time

The test binary for 64bit_child determines the bitness of the process
by searching the memory map for either 'librrpage.so' or
'librrpage_32.so'. This commit makes the test independent of the
SONAME of librrpage, instead relying on predefined architecture macros
since these should reflect the eventual process image bitness.

Author: Bob131

src/test/64bit_child.c

@@ -2,22 +2,16 @@
 
 #include "util.h"
 
-void callback(uint64_t env, char *name, __attribute__((unused)) map_properties_t* props) {
-  const char search[] = "librrpage.so";
-  if (strlen(name) > strlen(search)) {
-    if (sizeof(void*) == 4 &&
-        strcmp(name + strlen(name) - strlen(search), search) == 0)
-    {
-      int* rr_is_32bit = (int*)(uintptr_t)env;
-      *rr_is_32bit = 1;
-    }
-  }
-}
-
 static void skip_if_rr_32_bit_under_kernel_64_bit(void) {
-  FILE* maps_file = fopen("/proc/self/maps", "r");
-  int rr_is_32bit = 0;
-  iterate_maps((uintptr_t)&rr_is_32bit, callback, maps_file);
+  int rr_is_32bit;
+
+#ifdef __i386__
+  rr_is_32bit = 1;
+#elif defined(__x86_64__) || defined(__aarch64__)
+  rr_is_32bit = 0;
+#else
+# error "With what bitness are we compiling?"
+#endif
 
   struct utsname buf;
   if (uname(&buf) != 0)