[PATCH] elflint: fix undefined 'buffer_left' reference

[Sergei Trofimovich]

Link failure is reproducible on gcc-11.1.0 target:

```
$ autoreconf -i -f
$ ./configure --enable-maintainer-mode --disable-debuginfod \
    --host=x86_64-pc-linux-gnu \
    CFLAGS=-march=znver3 \
    CXXFLAGS=-march=znver3 \
    LDFLAGS=" "
$ make

  CCLD     elflint
ld: elflint.o: in function `check_attributes':
elflint.c:(.text+0xdcff): undefined reference to `buffer_left'
ld: elflint.c:(.text+0xe557): undefined reference to `buffer_left'
```

It happens due to possible external linkage of `buffer_left()`.

The change forces local linkkage to always use local definition
(either inline or out-of-line).

Reported-by: Toralf Förster
Bug: https://bugs.gentoo.org/794601
Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
---
 src/ChangeLog | 5 +++++
 src/elflint.c | 2 +-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/ChangeLog b/src/ChangeLog
index 2c7be185..e030de0d 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,8 @@
+2021-06-06  Sergei Trofimovich  <slyfox@gentoo.org>
+
+	* elflint.c (buffer_left): Mark as 'inline' to avoid external linkage
+	failure.
+
 2021-05-12  Dmitry V. Levin  <ldv@altlinux.org>
 
 	* elfcompress.c (process_file): Return 1 instead of -1 in case of an
diff --git a/src/elflint.c b/src/elflint.c
index 85cc7833..35b40500 100644
--- a/src/elflint.c
+++ b/src/elflint.c
@@ -3434,7 +3434,7 @@ buffer_pos (Elf_Data *data, const unsigned char *p)
   return p - (const unsigned char *) data->d_buf;
 }
 
-inline size_t
+static inline size_t
 buffer_left (Elf_Data *data, const unsigned char *p)
 {
   return (const unsigned char *) data->d_buf + data->d_size - p;
-- 
2.31.1