[committed] Fix build of libgcc on ports using FDPIC

[Jeff Law]

read_encoded_value_with_base has an ifdef'd code path conditional on 
__FDPIC__ which was calling _Unwind_gnu_Find_got without a prototype. 
This naturally caused various build failures.

This adds a suitable prototype.

Pushed to the trunk.
commit 4cef6daf40f4aefd748245a720955d4e52d1a81e
Author: Jeff Law <j...@ventanamicro.com>
Date:   Sat Dec 2 22:45:48 2023 -0700

    [committed] Fix build of libgcc on ports using FDPIC
    
    read_encoded_value_with_base has an ifdef'd code path conditional on 
__FDPIC__
    which was calling _Unwind_gnu_Find_got without a prototype.  This naturally
    caused various build failures.
    
    This adds a suitable prototype.
    
    Pushed to the trunk.
    
    libgcc
    
            * unwind-pe.h (_Unwind_gnu_Find_got): Add prototype.

diff --git a/libgcc/unwind-pe.h b/libgcc/unwind-pe.h
index 3f98c93589a..d714a27a935 100644
--- a/libgcc/unwind-pe.h
+++ b/libgcc/unwind-pe.h
@@ -173,6 +173,8 @@ read_sleb128 (const unsigned char *p, _sleb128_t *val)
   return p;
 }
 
+extern _Unwind_Ptr _Unwind_gnu_Find_got (_Unwind_Ptr);
+
 /* Load an encoded value from memory at P.  The value is returned in VAL;
    The function returns P incremented past the value.  BASE is as given
    by base_of_encoded_value for this encoding in the appropriate context.  */