Fix upper->lower case for /usr/lib/debug/.build-id/**.debug

[jankratochvil]

Summary

I have found the lookup by build-id (when lookup by /usr/lib/debug/path/name/exec.debug failed) does not work as LLDB tries the build-id hex string in uppercase but Fedora uses lowercase.
xubuntu-16.10 also uses lowercase during my test:

/usr/lib/debug/.build-id/6c/61f3566329f43d03f812ae7057e9e7391b5ff6.debug

So I do not see when it could work, I haven't found any such regression-looking change in GIT history.

[clayborg]

Many file systems are case insensitive so that is probably why it works on some computers.

[jankratochvil]

Simplify the testcase using: lldbutil.run_to_name_breakpoint

lldb/trunk/packages/Python/lldbsuite/test/linux/buildidcase/Makefile

+LEVEL = ../../make
+C_SOURCES := main.c
+LD_EXTRAS += -Wl,--build-id=sha1
+
+all: stripped.out
+
+.PHONY: .build-id
+stripped.out .build-id: a.out
+  $(OBJCOPY) -j .note.gnu.build-id -O binary $< tmp
+  rm -rf .build-id
+  fn=`od -An -tx1 <tmp|tr -d ' \n'|sed -e 's/^.\{32\}//' -e 's#^..#.build-id/&/#' -e 's#$$#.debug#'` && \
+  mkdir -p `dirname $$fn` && \
+  $(OBJCOPY) --only-keep-debug $< $$fn && \
+  $(OBJCOPY) --strip-all --add-gnu-debuglink=$$fn $< stripped.out
+  $(RM) tmp
+
+clean::
+  $(RM) -r stripped.out .build-id
+
+include $(LEVEL)/Makefile.rules

lldb/trunk/packages/Python/lldbsuite/test/linux/buildidcase/TestTargetSymbolsBuildidCase.py

+""" Testing separate debug info loading by its .build-id. """
+import os
+import time
+import lldb
+import sys
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+
+class TestTargetSymbolsBuildidCase(TestBase):
+
+    mydir = TestBase.compute_mydir(__file__)
+
+    @no_debug_info_test  # Prevent the genaration of the dwarf version of this test
+    @skipUnlessPlatform(['linux'])
+    def test_target_symbols_buildid_case(self):
+        self.build(clean=True)
+        exe = self.getBuildArtifact("stripped.out")
+
+        lldbutil.run_to_name_breakpoint(self, "main", exe_name = exe)

lldb/trunk/packages/Python/lldbsuite/test/linux/buildidcase/main.c

+int main() {
+  return 0;
+}

lldb/trunk/source/Host/common/Symbols.cpp

 #endif // LLVM_ON_WIN32
 
     std::string uuid_str;
     const UUID &module_uuid = module_spec.GetUUID();
     if (module_uuid.IsValid()) {
       // Some debug files are stored in the .build-id directory like this:
       //   /usr/lib/debug/.build-id/ff/e7fe727889ad82bb153de2ad065b2189693315.debug
       uuid_str = module_uuid.GetAsString("");
+      std::transform(uuid_str.begin(), uuid_str.end(), uuid_str.begin(),
+          ::tolower);
       uuid_str.insert(2, 1, '/');
       uuid_str = uuid_str + ".debug";
     }
 
     size_t num_directories = debug_file_search_paths.GetSize();
     for (size_t idx = 0; idx < num_directories; ++idx) {
       FileSpec dirspec = debug_file_search_paths.GetFileSpecAtIndex(idx);
       dirspec.ResolvePath();