Fix PERFETTO_BUILDFLAG_DEFINE_PERFETTO_ARCH_CPU_ARM64

This simplifies PERFETTO_BUILDFLAG_DEFINE_PERFETTO_ARCH_CPU_ARM64
and makes sure it's defined for all architectures.
Also removes PERFETTO_BUILDFLAG_DEFINE_PERFETTO_ARCH_CPU_X86_64
which isn't used.

Bug: 313377232
Change-Id: I1b13c007445af06664372b612dad611beb7dd059

include/perfetto/base/build_config.h

@@ -133,12 +133,10 @@
 //   http://msdn.microsoft.com/en-us/library/b0084kay.aspx
 //   http://www.agner.org/optimize/calling_conventions.pdf
 //   or with gcc, run: "echo | gcc -E -dM -"
-#if defined(_M_X64) || defined(__x86_64__)
-#define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_ARCH_CPU_ARM64() 0
-#define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_ARCH_CPU_X86_64() 1
-#elif defined(__aarch64__) || defined(_M_ARM64)
+#if defined(__aarch64__) || defined(_M_ARM64)
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_ARCH_CPU_ARM64() 1
-#define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_ARCH_CPU_X86_64() 0
+#else
+#define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_ARCH_CPU_ARM64() 0
 #endif
 
 // perfetto_build_flags.h contains the tweakable build flags defined via GN.