libpng: update to 1.2.43

third_party/libpng/pnggccrd.c

 /* pnggccrd.c was removed from libpng-1.2.20. */
 
 /* This code snippet is for use by configure's compilation test. */
 
 #if (!defined _MSC_VER) && \
     defined(PNG_ASSEMBLER_CODE_SUPPORTED) && \
     defined(PNG_MMX_CODE_SUPPORTED)
 
 int PNGAPI png_dummy_mmx_support(void);
 
 static int _mmx_supported = 2; // 0: no MMX; 1: MMX supported; 2: not tested
 
 int PNGAPI
 png_dummy_mmx_support(void) __attribute__((noinline));
 
 int PNGAPI
 png_dummy_mmx_support(void)
 {
    int result;
-#if defined(PNG_MMX_CODE_SUPPORTED)  // superfluous, but what the heck
+#ifdef PNG_MMX_CODE_SUPPORTED  // superfluous, but what the heck
     __asm__ __volatile__ (
-#if defined(__x86_64__)
+#ifdef __x86_64__
         "pushq %%rbx          \n\t"  // rbx gets clobbered by CPUID instruction
         "pushq %%rcx          \n\t"  // so does rcx...
         "pushq %%rdx          \n\t"  // ...and rdx (but rcx & rdx safe on Linux)
         "pushfq               \n\t"  // save Eflag to stack
         "popq %%rax           \n\t"  // get Eflag from stack into rax
         "movq %%rax, %%rcx    \n\t"  // make another copy of Eflag in rcx
         "xorl $0x200000, %%eax \n\t" // toggle ID bit in Eflag (i.e., bit 21)
         "pushq %%rax          \n\t"  // save modified Eflag back to stack
         "popfq                \n\t"  // restore modified value to Eflag reg
         "pushfq               \n\t"  // save Eflag to stack
@@ skipping 31 matching lines @@
         "andl $0x800000, %%edx \n\t" // mask out all bits but MMX bit (23)
         "cmpl $0, %%edx       \n\t"  // 0 = MMX not supported
         "jz 0f                \n\t"  // non-zero = yes, MMX IS supported
 
         "movl $1, %%eax       \n\t"  // set return value to 1
         "jmp  1f              \n\t"  // DONE:  have MMX support
 
     "0:                       \n\t"  // .NOT_SUPPORTED: target label for jump instructions
         "movl $0, %%eax       \n\t"  // set return value to 0
     "1:                       \n\t"  // .RETURN: target label for jump instructions
-#if defined(__x86_64__)
+#ifdef __x86_64__
         "popq %%rdx           \n\t"  // restore rdx
         "popq %%rcx           \n\t"  // restore rcx
         "popq %%rbx           \n\t"  // restore rbx
 #else
         "popl %%edx           \n\t"  // restore edx
         "popl %%ecx           \n\t"  // restore ecx
         "popl %%ebx           \n\t"  // restore ebx
 #endif
 
 //      "ret                  \n\t"  // DONE:  no MMX support
                                      // (fall through to standard C "ret")
 
         : "=a" (result)              // output list
 
         :                            // any variables used on input (none)
 
                                      // no clobber list
 //      , "%ebx", "%ecx", "%edx"     // GRR:  we handle these manually
 //      , "memory"   // if write to a variable gcc thought was in a reg
 //      , "cc"       // "condition codes" (flag bits)
     );
     _mmx_supported = result;
 #else
     _mmx_supported = 0;
 #endif /* PNG_MMX_CODE_SUPPORTED */
 
     return _mmx_supported;
 }
 #endif