Revert "[msan] Increase kNumStackOriginDescrs constant (#92838)"

This reverts commit 57a5079.

Reason: buildbot breakage
(https://lab.llvm.org/buildbot/#/builders/57/builds/35160)

compiler-rt/lib/msan/msan.cpp

@@ -100,11 +100,7 @@ int msan_report_count = 0;
 
 // Array of stack origins.
 // FIXME: make it resizable.
-// Although BSS memory doesn't cost anything until used, it is limited to 2GB
-// in some configurations (e.g., "relocation R_X86_64_PC32 out of range:
-// ... is not in [-2147483648, 2147483647]; references section '.bss'").
-// We use kNumStackOriginDescrs * (sizeof(char*) + sizeof(uptr)) == 64MB.
-static const uptr kNumStackOriginDescrs = 4 * 1024 * 1024;
+static const uptr kNumStackOriginDescrs = 1024 * 1024;
 static const char *StackOriginDescr[kNumStackOriginDescrs];
 static uptr StackOriginPC[kNumStackOriginDescrs];
 static atomic_uint32_t NumStackOriginDescrs;