gnu: gcc-arm-none-eabi-4.9: Fix incompatible redeclaration.

* gnu/packages/patches/gcc-4.9-inline.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/embedded.scm (gcc-arm-none-eabi-4.9)[source]: Use it.

gnu/local.mk

@@ -1155,6 +1155,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/gcc-cross-gxx-include-dir.patch          \
   %D%/packages/patches/gcc-fix-texi2pod.patch			\
   %D%/packages/patches/gcc-4.8-libsanitizer-fix.patch		\
+  %D%/packages/patches/gcc-4.9-inline.patch		\
   %D%/packages/patches/gcc-4.9-libsanitizer-fix.patch		\
   %D%/packages/patches/gcc-4.9-libsanitizer-ustat.patch		\
   %D%/packages/patches/gcc-libsanitizer-ustat.patch		\

gnu/packages/embedded.scm

@@ -98,12 +98,14 @@
           (base32
            "113r98kygy8rrjfv2pd3z6zlfzbj543pq7xyq8bgh72c608mmsbr"))
 
-         ;; Remove the one patch that doesn't apply to this 4.9 snapshot (the
-         ;; patch is for 4.9.4 and later but this svn snapshot is older).
-         (patches (remove (lambda (patch)
+         (patches (cons (search-patch "gcc-4.9-inline.patch")
+                        ;; Remove the one patch that doesn't apply to this 4.9
+                        ;; snapshot (the patch is for 4.9.4 and later but this
+                        ;; svn snapshot is older).
+                        (remove (lambda (patch)
                                   (string=? (basename patch)
                                             "gcc-arm-bug-71399.patch"))
-                          (origin-patches (package-source xgcc))))))
+                                (origin-patches (package-source xgcc)))))))
       (native-inputs
        `(("flex" ,flex)
          ("gcc@5" ,gcc-5)

gnu/packages/patches/gcc-4.9-inline.patch

@@ -0,0 +1,13 @@
+diff -ru a/gcc/cp/cfns.h b/gcc/cp/cfns.h
+--- a/gcc/cp/cfns.h	1970-01-01 01:00:01.000000000 +0100
++++ b/gcc/cp/cfns.h	2023-04-23 09:23:28.883815598 +0200
+@@ -53,6 +53,9 @@
+ static unsigned int hash (const char *, unsigned int);
+ #ifdef __GNUC__
+ __inline
++#ifdef __GNUC_STDC_INLINE__
++__attribute__ ((__gnu_inline__))
++#endif
+ #endif
+ const char * libc_name_p (const char *, unsigned int);
+ /* maximum key range = 391, duplicates = 0 */