Add configuration support to detect and use LLVM libraries.

This adds the --with-llvm configuration flag.  It's used to find
the path to LLVM's llvm-config which produces the pre-processor and
linker flags needed to include LLVM's ProfileData library.

This change only includes the necessary configury bits to support
building with LLVM libraries.  It does not change the LLVM profile
converter at all.

Makefile.am

@@ -13,7 +13,8 @@ COMMON_PROFILE_CREATOR_FILES = addr2line.cc gcov.cc instruction_map.cc \
 
 bin_PROGRAMS = create_gcov
 create_gcov_SOURCES = $(COMMON_PROFILE_CREATOR_FILES) create_gcov.cc
-create_gcov_LDADD = libquipper.a libglog.a libsymbolize.a libgflags.a
+create_gcov_LDADD = $(LLVM_LDFLAGS) libquipper.a libglog.a libsymbolize.a libgflags.a
+create_gcov_CXXFLAGS = $(LLVM_CXXFLAGS)
 
 bin_PROGRAMS += dump_gcov
 dump_gcov_SOURCES = profile_reader.cc symbol_map.cc module_grouper.cc gcov.cc \
@@ -22,26 +23,31 @@ dump_gcov_LDADD = libglog.a libgflags.a libsymbolize.a
 
 bin_PROGRAMS += sample_merger
 sample_merger_SOURCES = $(COMMON_PROFILE_CREATOR_FILES) sample_merger.cc
-sample_merger_LDADD = libquipper.a libglog.a libsymbolize.a libgflags.a
+sample_merger_LDADD = $(LLVM_LDFLAGS) libquipper.a libglog.a libsymbolize.a libgflags.a
+sample_merger_CXXFLAGS = $(LLVM_CXXFLAGS)
 
 bin_PROGRAMS += profile_merger
 profile_merger_SOURCES = $(COMMON_PROFILE_CREATOR_FILES) profile_reader.cc \
                          profile_merger.cc
-profile_merger_LDADD = libquipper.a libglog.a libsymbolize.a libgflags.a
+profile_merger_CXXFLAGS = $(LLVM_CXXFLAGS)
+profile_merger_LDADD = $(LLVM_LDFLAGS) libquipper.a libglog.a libsymbolize.a libgflags.a
 
 bin_PROGRAMS += profile_diff
 profile_diff_SOURCES = $(COMMON_PROFILE_CREATOR_FILES) profile_reader.cc \
                        profile_diff.cc
-profile_diff_LDADD = libquipper.a libglog.a libsymbolize.a libgflags.a
+profile_diff_LDADD = $(LLVM_LDFLAGS) libquipper.a libglog.a libsymbolize.a libgflags.a
+profile_diff_CXXFLAGS = $(LLVM_CXXFLAGS)
 
 bin_PROGRAMS += profile_update
 profile_update_SOURCES = $(COMMON_PROFILE_CREATOR_FILES) profile_reader.cc \
                          profile_update.cc
-profile_update_LDADD = libquipper.a libglog.a libsymbolize.a libgflags.a
+profile_update_LDADD = $(LLVM_LDFLAGS) libquipper.a libglog.a libsymbolize.a libgflags.a
+profile_update_CXXFLAGS = $(LLVM_CXXFLAGS)
 
 bin_PROGRAMS += create_llvm_prof
 create_llvm_prof_SOURCES = $(COMMON_PROFILE_CREATOR_FILES) create_llvm_prof.cc
-create_llvm_prof_LDADD = libquipper.a libglog.a libsymbolize.a libgflags.a
+create_llvm_prof_LDADD = $(LLVM_LDFLAGS) libquipper.a libglog.a libsymbolize.a libgflags.a
+create_llvm_prof_CXXFLAGS = $(LLVM_CXXFLAGS)
 
 noinst_LIBRARIES = libquipper.a
 libquipper_a_SOURCES = chromiumos-wide-profiling/address_mapper.cc chromiumos-wide-profiling/perf_reader.cc \