gnuefi: preserve .gnu.hash sections (unbreaks elilo on IA-64)

Gentoo has slightly modified linker defaults: --hash-style=gnu
This means all ELF files in system have '.gnu.hash' section
but no '.hash' section.

gnuefi's ldscript did not account for it and as a result
one symbol 'ImageBase' did not resolve locally for elilo.so
and caused 'elilo' to fail to load by ia64 EFI:
  Loading.: Gentoo (try new elilo)
  ImageAddress: pointer is outside of image
  ImageAddress: pointer is outside of image

Those two relocations come from crt0-efi-ia64.S PE32 entry point
fdescr:

```
    #define IMAGE_REL_BASED_DIR64<->10
    .section .reloc, "a"
    data4   _start_plabel // Page RVA
    data4   12            // Block Size (2*4+2*2)
    data2   (IMAGE_REL_BASED_DIR64<<12) +  0 // reloc for plabel's entry point
    data2   (IMAGE_REL_BASED_DIR64<<12) +  8 // reloc for plabel's global pointer
```

These refer ImageBase.

The change adds '.gnu.hash' collection (follows existing '.hash'
collection).

Tested on IA-64 by successfully booting elilo-3.16.

Bug: https://bugs.gentoo.org/575300
Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>

README.gnuefi

@@ -231,11 +231,17 @@ and page sized.These eight sections are used to group together the much
 greater number of sections that are typically present in ELF object files.
 Specifically:
 
- .hash
+ .hash (and/or .gnu.hash)
 	Collects the ELF .hash info (this section _must_ be the first
 	section in order to build a shared object file; the section is
 	not actually loaded or used at runtime).
 
+	GNU binutils provides a mechanism to generate different hash info
+	via --hash-style=<sysv|gnu|both> option. In this case output
+	shared object will contain .hash section, .gnu.hash section or
+	both. In order to generate correct output linker script preserves
+	both types of hash sections.
+
  .text
 	Collects all sections containing executable code.
 

gnuefi/elf_ia32_efi.lds

@@ -5,7 +5,9 @@ SECTIONS
 {
   . = 0;
   ImageBase = .;
-  .hash : { *(.hash) }	/* this MUST come first! */
+  /* .hash and/or .gnu.hash MUST come first! */
+  .hash : { *(.hash) }
+  .gnu.hash : { *(.gnu.hash) }
   . = ALIGN(4096);
   .text :
   {

gnuefi/elf_ia32_fbsd_efi.lds

@@ -5,7 +5,9 @@ SECTIONS
 {
   . = 0;
   ImageBase = .;
-  .hash : { *(.hash) }	/* this MUST come first! */
+  /* .hash and/or .gnu.hash MUST come first! */
+  .hash : { *(.hash) }
+  .gnu.hash : { *(.gnu.hash) }
   . = ALIGN(4096);
   .text :
   {

gnuefi/elf_ia64_efi.lds

@@ -5,7 +5,9 @@ SECTIONS
 {
   . = 0;
   ImageBase = .;
-  .hash : { *(.hash) }	/* this MUST come first! */
+  /* .hash and/or .gnu.hash MUST come first! */
+  .hash : { *(.hash) }
+  .gnu.hash : { *(.gnu.hash) }
   . = ALIGN(4096);
   .text :
   {

gnuefi/elf_x86_64_efi.lds

@@ -6,7 +6,9 @@ SECTIONS
 {
   . = 0;
   ImageBase = .;
-  .hash : { *(.hash) }	/* this MUST come first! */
+  /* .hash and/or .gnu.hash MUST come first! */
+  .hash : { *(.hash) }
+  .gnu.hash : { *(.gnu.hash) }
   . = ALIGN(4096);
   .eh_frame : 
   { 

gnuefi/elf_x86_64_fbsd_efi.lds

@@ -6,7 +6,9 @@ SECTIONS
 {
   . = 0;
   ImageBase = .;
-  .hash : { *(.hash) }	/* this MUST come first! */
+  /* .hash and/or .gnu.hash MUST come first! */
+  .hash : { *(.hash) }
+  .gnu.hash : { *(.gnu.hash) }
   . = ALIGN(4096);
   .eh_frame : 
   {