[rfc] dont use absolute paths in ldscripts if they arent needed

[Mike Frysinger <vapier at gentoo dot org>]

i've been playing with cross-compilers in Gentoo when i noticed that the 
ldscripts installed by glibc always use full paths.  in a normal setup, these 
are clearly required as libc.so.6 goes in /lib/ while libc.so goes 
in /usr/lib/.  in a cross-compiler setup though, you usually have libc.so.6 
and libc.so in the same directory (like /usr/target/lib/).  encoding this 
full path can cause problems when using sysroot options with binutils and 
gcc.  crosstool gets around this by simply running a sed on the linker 
scripts and deleting all leading path elements.  that seems kind of hackish 
so i whipped together a patch that i've been testing in Gentoo with mips64 
multilib cross-compilers and some x86/amd64/ppc native installs that updates 
the glibc build files to only generate absolute paths in the linker scripts 
when $(slibdir) and $(libdir) are not the same.
-mike

2006-04-02  Mike Frysinger  <vapier@gentoo.org>

	* Makerules ($(inst_libdir)/libc.so): Only use absolute paths necessary.
	* nptl/Makerules ($(inst_libdir)/libpthread.so): Likewise.

--- libc/Makerules
+++ libc/Makerules
@@ -972,6 +972,14 @@ ifndef subdir
 # We need to use absolute paths since otherwise local copies (if they exist)
 # of the files are taken by the linker.
 install: $(inst_libdir)/libc.so
+
+ifeq ($(slibdir),$(libdir))
+ldscript_slibdir =
+ldscript_libdir =
+else
+ldscript_slibdir = $(slibdir)/
+ldscript_libdir = $(libdir)/
+endif
 $(inst_libdir)/libc.so: $(common-objpfx)format.lds \
 			$(common-objpfx)libc.so$(libc.so-version) \
 			$(inst_libdir)/$(patsubst %,$(libtype.oS),\
@@ -981,9 +989,9 @@ $(inst_libdir)/libc.so: $(common-objpfx)
 	 echo '   Use the shared library, but some functions are only in';\
 	 echo '   the static library, so try that secondarily.  */';\
 	 cat $<; \
-	 echo 'GROUP ( $(slibdir)/libc.so$(libc.so-version)' \
-	      '$(libdir)/$(patsubst %,$(libtype.oS),$(libprefix)$(libc-name))'\
-	      ' AS_NEEDED (' $(slibdir)/$(rtld-installed-name) ') )' \
+	 echo 'GROUP ( $(ldscript_slibdir)libc.so$(libc.so-version)' \
+	      '$(ldscript_libdir)$(patsubst %,$(libtype.oS),$(libprefix)$(libc-name))'\
+	      ' AS_NEEDED (' $(ldscript_slibdir)$(rtld-installed-name) ') )' \
 	) > $@.new
 	mv -f $@.new $@
 
--- libc/nptl/Makefile
+++ libc/nptl/Makefile
@@ -368,6 +368,13 @@ lib-noranlib: $(addprefix $(objpfx),$(ex
 # of the files are taken by the linker.
 install: $(inst_libdir)/libpthread.so
 
+ifeq ($(slibdir),$(libdir))
+ldscript_slibdir =
+ldscript_libdir =
+else
+ldscript_slibdir = $(slibdir)/
+ldscript_libdir = $(libdir)/
+endif
 $(inst_libdir)/libpthread.so: $(common-objpfx)format.lds \
 			      $(objpfx)libpthread.so$(libpthread.so-version) \
 			      $(inst_libdir)/$(patsubst %,$(libtype.oS),\
@@ -377,8 +384,8 @@ $(inst_libdir)/libpthread.so: $(common-o
 	 echo '   Use the shared library, but some functions are only in';\
 	 echo '   the static library, so try that secondarily.  */';\
 	 cat $<; \
-	 echo 'GROUP ( $(slibdir)/libpthread.so$(libpthread.so-version)' \
-	      '$(libdir)/$(patsubst %,$(libtype.oS),$(libprefix)pthread)'\
+	 echo 'GROUP ( $(ldscript_slibdir)libpthread.so$(libpthread.so-version)' \
+	      '$(ldscript_libdir)$(patsubst %,$(libtype.oS),$(libprefix)pthread)'\
 	      ')' \
 	) > $@.new
 	mv -f $@.new $@