Fix symbolizer markup backtrace build/test.

This corrects a Darwin build failure due to a missing stub and an
environment-specific Linux test failure due to an overly restrictive
test regex. This also backs out of the previous fix attempt; %p is
intended to be printed and parsed with the semantics of #.

Author: mysterymath

llvm/lib/Support/Unix/Signals.inc

@@ -539,7 +539,7 @@ public:
       uintptr_t StartAddress = Info->dlpi_addr + Phdr->p_vaddr;
       uintptr_t ModuleRelativeAddress = Phdr->p_vaddr;
       std::array<char, 4> ModeStr = modeStrFromFlags(Phdr->p_flags);
-      OS << format("{{{mmap:%016x:%x:load:%d:%s:%016x}}}\n", StartAddress,
+      OS << format("{{{mmap:%#016x:%#x:load:%d:%s:%#016x}}}\n", StartAddress,
                    Phdr->p_memsz, ModuleCount, &ModeStr[0],
                    ModuleRelativeAddress);
     }
@@ -656,6 +656,10 @@ static bool findModulesAndOffsets(void **StackTrace, int Depth,
   return true;
 }
 
+static bool printMarkupContext(llvm::raw_ostream &OS,
+                               const char *MainExecutableName) {
+  return false;
+}
 #else
 /// Backtraces are not enabled or we don't yet know how to find all loaded DSOs
 /// on this platform.

llvm/unittests/Support/SignalsTest.cpp

@@ -25,6 +25,10 @@ using testing::Not;
 
 #define TAG_BEGIN "\\{\\{\\{"
 #define TAG_END "\\}\\}\\}"
+// %p in the Symbolizer Markup Format spec
+#define P_REGEX "(0+|0x[0-9a-fA-F]+)"
+// %i in the Symbolizer Markup Format spec
+#define I_REGEX "(0x[0-9a-fA-F]+|0[0-7]+|[0-9]+)"
 
 #if defined(HAVE_BACKTRACE) && ENABLE_BACKTRACES && HAVE_LINK_H &&             \
     (defined(__linux__) || defined(__FreeBSD__) ||                             \
@@ -43,14 +47,10 @@ TEST(SignalsTest, PrintsSymbolizerMarkup) {
                            "module:0:[^:]*SupportTests:elf:[0-9a-f]+" TAG_END
                            ".*"));
   // Text segment for main binary
-  EXPECT_THAT(
-      Res,
-      MatchesRegex(".*" TAG_BEGIN
-                   "mmap:[0-9a-f]+:[0-9a-f]+:load:0:rx:[0-9a-f]+" TAG_END
-                   ".*"));
+  EXPECT_THAT(Res, MatchesRegex(".*" TAG_BEGIN "mmap:" P_REGEX ":" I_REGEX
+                                ":load:0:rx:" P_REGEX TAG_END ".*"));
   // Backtrace line
-  EXPECT_THAT(Res, MatchesRegex(".*" TAG_BEGIN "bt:0:[0-9a-f]+"
-                                ".*"));
+  EXPECT_THAT(Res, MatchesRegex(".*" TAG_BEGIN "bt:0:" P_REGEX ".*"));
 }
 
 TEST(SignalsTest, SymbolizerMarkupDisabled) {