bootstrap/119680 - fix cross-compiler build with --enable-host-shared

It seems that at least when cross-compiling at least collect2 pulls
in objects from libbacktrace.a which is linked via LIBDEPS.  But
libbacktrace for the host is only built -fPIC with --enable-host-shared
but not -fPIE with --enable-host-pie so this fails.  The following
teaches libbacktrace about --enable-host-pie and handles it similar
to libcpp.

	PR bootstrap/119680
libbacktrace/
	* configure.ac (--enable-host-pie): Handle by setting PIC_FLAG
	to -fPIE.
	* configure: Regenerate.

configure

@@ -812,6 +812,7 @@ enable_darwin_at_rpath
 enable_largefile
 enable_werror
 with_system_libunwind
+enable_host_pie
 enable_host_shared
 '
       ac_precious_vars='build_alias
@@ -1461,6 +1462,7 @@ Optional Features:
                           rpaths to be added to executables
   --disable-largefile     omit support for large files
   --disable-werror        disable building with -Werror
+  --enable-host-pie       build host code as PIE
   --enable-host-shared    build host code as shared libraries
 
 Optional Packages:
@@ -11395,7 +11397,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11398 "configure"
+#line 11400 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11501,7 +11503,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11504 "configure"
+#line 11506 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -12190,12 +12192,18 @@ $as_echo "#define HAVE_GETIPINFO 1" >>confdefs.h
   fi
 fi
 
+# Enable --enable-host-pie.
+# Check whether --enable-host-pie was given.
+if test "${enable_host_pie+set}" = set; then :
+  enableval=$enable_host_pie; PIC_FLAG=-fPIE
+else
+  PIC_FLAG=
+fi
+
 # Enable --enable-host-shared.
 # Check whether --enable-host-shared was given.
 if test "${enable_host_shared+set}" = set; then :
   enableval=$enable_host_shared; PIC_FLAG=-fPIC
-else
-  PIC_FLAG=
 fi
 
 

configure.ac

@@ -176,11 +176,16 @@ else
   fi
 fi
 
+# Enable --enable-host-pie.
+AC_ARG_ENABLE(host-pie,
+[AS_HELP_STRING([--enable-host-pie],
+                [build host code as PIE])],
+[PIC_FLAG=-fPIE], [PIC_FLAG=])
 # Enable --enable-host-shared.
 AC_ARG_ENABLE(host-shared,
 [AS_HELP_STRING([--enable-host-shared],
 		[build host code as shared libraries])],
-[PIC_FLAG=-fPIC], [PIC_FLAG=])
+[PIC_FLAG=-fPIC])
 AC_SUBST(PIC_FLAG)
 
 # Test for __sync support.