Redirect `GetPageSize()` to C library `getpagesize()` on Hexagon DSP.

PiperOrigin-RevId: 590669848
Change-Id: Ibc703b0fbedede86ddaa9682049b7dcc2250fbfb

absl/base/internal/low_level_alloc.cc

@@ -329,7 +329,7 @@ size_t GetPageSize() {
   SYSTEM_INFO system_info;
   SYSTEM_INFO system_info;
   GetSystemInfo(&system_info);
   GetSystemInfo(&system_info);
   return std::max(system_info.dwPageSize, system_info.dwAllocationGranularity);
   return std::max(system_info.dwPageSize, system_info.dwAllocationGranularity);
-#elif defined(__wasm__) || defined(__asmjs__)
+#elif defined(__wasm__) || defined(__asmjs__) || defined(__hexagon__)
   return getpagesize();
   return getpagesize();
 #else
 #else
   return static_cast<size_t>(sysconf(_SC_PAGESIZE));
   return static_cast<size_t>(sysconf(_SC_PAGESIZE));