objtool: Rename elf_open() to prevent conflict with libelf from elftoolchain

The elftoolchain version of libelf has a function named elf_open().

The function name isn't quite accurate anyway, since it also reads all
the ELF data.  Rename it to elf_read(), which is more accurate.

[ jpoimboe: rename to elf_read(); write commit description ]
Signed-off-by: Michael Forney <mforney@mforney.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/7ce2d1b35665edf19fd0eb6fbc0b17b81a48e62f.1562793604.git.jpoimboe@redhat.com

tools/objtool/check.c

@@ -2407,7 +2407,7 @@ int check(const char *_objname, bool orc)
 
 	objname = _objname;
 
-	file.elf = elf_open(objname, orc ? O_RDWR : O_RDONLY);
+	file.elf = elf_read(objname, orc ? O_RDWR : O_RDONLY);
 	if (!file.elf)
 		return 1;
 

tools/objtool/elf.c

@@ -401,7 +401,7 @@ static int read_relas(struct elf *elf)
 	return 0;
 }
 
-struct elf *elf_open(const char *name, int flags)
+struct elf *elf_read(const char *name, int flags)
 {
 	struct elf *elf;
 	Elf_Cmd cmd;

tools/objtool/elf.h

@@ -74,7 +74,7 @@ struct elf {
 };
 
 
-struct elf *elf_open(const char *name, int flags);
+struct elf *elf_read(const char *name, int flags);
 struct section *find_section_by_name(struct elf *elf, const char *name);
 struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset);
 struct symbol *find_symbol_by_name(struct elf *elf, const char *name);