builtins: fix a -Wshorten-64-to-32 in gcc_personality_v0

[phosek]

LGTM

[jrtc27]

Been that way since the initial import in fd089990f76ec6392dbd0138ab874d90c632d2a4

[MaskRay]

This warning is under -Wnon-gcc > -Wconversion > -Wshorten-64-to-32, not enabled by llvm/cmake/modules/HandleLLVMOptions.cmake, so nobody noticed :)

compiler-rt/lib/builtins/gcc_personality_v0.c

if (lpStartEncoding != DW_EH_PE_omit) {
     readEncodedPointer(&lsda, lpStartEncoding);
   }
   uint8_t ttypeEncoding = *lsda++;
   if (ttypeEncoding != DW_EH_PE_omit) {
     readULEB128(&lsda);
   }
   // Walk call-site table looking for range that includes current PC.
   uint8_t callSiteEncoding = *lsda++;
-  uint32_t callSiteTableLength = readULEB128(&lsda);
+  size_t callSiteTableLength = readULEB128(&lsda);
   const uint8_t *callSiteTableStart = lsda;
   const uint8_t *callSiteTableEnd = callSiteTableStart + callSiteTableLength;
   const uint8_t *p = callSiteTableStart;
   while (p < callSiteTableEnd) {
     uintptr_t start = readEncodedPointer(&p, callSiteEncoding);
     size_t length = readEncodedPointer(&p, callSiteEncoding);
     size_t landingPad = readEncodedPointer(&p, callSiteEncoding);
     readULEB128(&p); // action value not used for C code