cmake: fix uses of undefined macro identifiers (-Wundef)

src/cpuinfo/SDL_cpuinfo.c

@@ -57,7 +57,7 @@
 #elif defined(__FreeBSD__) && defined(__powerpc__)
 #include <machine/cpu.h>
 #include <sys/auxv.h>
-#elif SDL_ALTIVEC_BLITTERS && HAVE_SETJMP
+#elif defined(SDL_ALTIVEC_BLITTERS) && defined(HAVE_SETJMP)
 #include <signal.h>
 #include <setjmp.h>
 #endif
@@ -123,7 +123,7 @@
 #define CPU_CFG2_LSX  (1 << 6)
 #define CPU_CFG2_LASX (1 << 7)
 
-#if SDL_ALTIVEC_BLITTERS && HAVE_SETJMP && !__MACOSX__ && !__OpenBSD__ && !__FreeBSD__
+#if defined(SDL_ALTIVEC_BLITTERS) && defined(HAVE_SETJMP) && !defined(__MACOSX__) && !defined(__OpenBSD__) && !defined(__FreeBSD__)
 /* This is the brute force way of detecting instruction sets...
    the idea is borrowed from the libmpeg2 library - thanks!
  */
@@ -352,7 +352,7 @@ static int CPU_haveAltiVec(void)
     elf_aux_info(AT_HWCAP, &cpufeatures, sizeof(cpufeatures));
     altivec = cpufeatures & PPC_FEATURE_HAS_ALTIVEC;
     return altivec;
-#elif SDL_ALTIVEC_BLITTERS && HAVE_SETJMP
+#elif defined(SDL_ALTIVEC_BLITTERS) && defined(HAVE_SETJMP)
     void (*handler)(int sig);
     handler = signal(SIGILL, illegal_instruction);
     if (setjmp(jmpbuf) == 0) {
@@ -468,9 +468,9 @@ static int CPU_haveNEON(void)
     return IsProcessorFeaturePresent(PF_ARM_NEON_INSTRUCTIONS_AVAILABLE) != 0;
 #elif (defined(__ARM_ARCH) && (__ARM_ARCH >= 8)) || defined(__aarch64__)
     return 1; /* ARMv8 always has non-optional NEON support. */
-#elif __VITA__
+#elif defined(__VITA__)
     return 1;
-#elif __3DS__
+#elif defined(__3DS__)
     return 0;
 #elif defined(__APPLE__) && defined(__ARM_ARCH) && (__ARM_ARCH >= 7)
     /* (note that sysctlbyname("hw.optional.neon") doesn't work!) */