musl: backport a fix that caused the wrong relocations to be emitted on some architectures

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

SVN-Revision: 48444

toolchain/musl/patches/001-eliminate-protected-visibility-data-in-libc.so-with-.patch

@@ -0,0 +1,55 @@
+From: Rich Felker <dalias@aerifal.cx>
+Date: Tue, 29 Sep 2015 02:44:05 +0000
+Subject: [PATCH] eliminate protected-visibility data in libc.so with vis.h
+ preinclude
+
+some newer binutils versions print scary warnings about protected data
+because most gcc versions fail to produce the right address
+references/relocations for such data that might be subject to copy
+relocations. originally vis.h explicitly assigned default visibility
+to all public data symbols to avoid this issue, but commit
+b8dda24fe1caa901a99580f7a52defb95aedb67c removed this treatment for
+stdin/out/err to work around a gcc 3.x bug, and since they don't
+actually need it (because taking their addresses is not valid C).
+
+instead, a check for the gcc 3.x bug is added to the configure check
+for vis.h preinclude support; this feature will simply be disabled
+when using a buggy version of gcc.
+---
+
+--- a/configure
++++ b/configure
+@@ -476,10 +476,18 @@ if test "x$visibility" = xauto ; then
+ # - the -include option
+ # - the attributes/pragmas used in vis.h
+ # - linking code that takes the address of protected symbols
++# - gcc 3.x bug that wrongly claims declarations mismatch
+ printf "checking whether global visibility preinclude works... "
+-echo 'int (*fp)(void);' > "$tmpc"
+-echo 'int foo(void) { }' >> "$tmpc"
+-echo 'int bar(void) { fp = foo; return foo(); }' >> "$tmpc"
++cat > "$tmpc" <<EOF
++__attribute__((__visibility__("default")))
++extern struct a *const x;
++typedef struct a b;
++extern b *const x;
++b *const x;
++int (*fp)(void);
++int foo(void) { }
++int bar(void) { fp = foo; return foo(); }
++EOF
+ if $CC $CFLAGS_C99FSE $CPPFLAGS $CFLAGS \
+   -DSHARED -fPIC -I./src/internal -include vis.h \
+   -nostdlib -shared -Wl,-Bsymbolic-functions \
+--- a/src/internal/vis.h
++++ b/src/internal/vis.h
+@@ -12,6 +12,9 @@
+  * exported data symbols. */
+ 
+ __attribute__((__visibility__("default")))
++extern struct _IO_FILE *const stdin, *const stdout, *const stderr;
++
++__attribute__((__visibility__("default")))
+ extern int optind, opterr, optopt, optreset, __optreset, getdate_err, h_errno, daylight, __daylight, signgam, __signgam;
+ 
+ __attribute__((__visibility__("default")))