[glibc] elf: Support lld-style link map for librtld.map

[Adhemerval Zanella <azanella@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=eb06601bb4187d8f5a9f55c2d212747869f63fe1

commit eb06601bb4187d8f5a9f55c2d212747869f63fe1
Author: Fangrui Song <maskray@google.com>
Date:   Tue Apr 21 13:28:42 2020 -0300

    elf: Support lld-style link map for librtld.map
    
    GNU ld and gold's -Map include a line like:
    
      path/to/build/libc_pic.a(check_fds.os)
    
    lld -Map does not have the archive member list, but we can still derive the
    members from the following output
    
                 VMA              LMA     Size Align Out     In      Symbol
    ...
               1a1c0            1a1c0       e2    16         path/to/build/libc_pic.a(check_fds.os):(.text)

Diff:
---
 elf/Makefile | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/elf/Makefile b/elf/Makefile
index 9b1d58c7ad..6919e53c14 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -514,9 +514,10 @@ $(objpfx)librtld.map: $(objpfx)dl-allobjs.os $(common-objpfx)libc_pic.a
 	rm -f $@.o
 	mv -f $@T $@
 
+# For lld, skip preceding addresses and values before matching the archive and the member.
 $(objpfx)librtld.mk: $(objpfx)librtld.map Makefile
 	LC_ALL=C \
-	sed -n 's@^$(common-objpfx)\([^(]*\)(\([^)]*\.os\)) *.*$$@\1 \2@p' \
+	sed -n 's@^[0-9a-f ]*$(common-objpfx)\([^(]*\)(\([^)]*\.os\)) *.*$$@\1 \2@p' \
 	    $< | \
 	while read lib file; do \
 	  case $$lib in \