Add support for sparc and sparc64 (#899)

Fixes #893

absl/base/internal/direct_mmap.h

@@ -77,7 +77,8 @@ inline void* DirectMmap(void* start, size_t length, int prot, int flags, int fd,
     (defined(__mips__) && _MIPS_SIM == _MIPS_SIM_ABI32) ||                   \
     (defined(__PPC__) && !defined(__PPC64__)) ||                             \
     (defined(__riscv) && __riscv_xlen == 32) ||                              \
-    (defined(__s390__) && !defined(__s390x__))
+    (defined(__s390__) && !defined(__s390x__)) ||                            \
+    (defined(__sparc__) && !defined(__arch64__))
   // On these architectures, implement mmap with mmap2.
   static int pagesize = 0;
   if (pagesize == 0) {

absl/debugging/internal/examine_stack.cc

@@ -63,6 +63,10 @@ void* GetProgramCounter(void* vuc) {
     return reinterpret_cast<void*>(context->uc_mcontext.psw.addr & 0x7fffffff);
 #elif defined(__s390__) && defined(__s390x__)
     return reinterpret_cast<void*>(context->uc_mcontext.psw.addr);
+#elif defined(__sparc__) && !defined(__arch64__)
+    return reinterpret_cast<void*>(context->uc_mcontext.gregs[19]);
+#elif defined(__sparc__) && defined(__arch64__)
+    return reinterpret_cast<void*>(context->uc_mcontext.mc_gregs[19]);
 #elif defined(__x86_64__)
     if (16 < ABSL_ARRAYSIZE(context->uc_mcontext.gregs))
       return reinterpret_cast<void*>(context->uc_mcontext.gregs[16]);