Merge branch 'fix-gnu-make-glob' into 'master'

fix: GNU seems to prefer its own glob.h

See merge request redox-os/relibc!598

src/header/glob/mod.rs

@@ -41,6 +41,7 @@ pub const GLOB_ABORTED: c_int = 2;
 // Pattern does not match any existing pathname, and GLOB_NOCHECK was not set
 pub const GLOB_NOMATCH: c_int = 3;
 
+#[linkage = "weak"] // GNU prefers its own glob e.g. in Make
 #[repr(C)]
 #[derive(Debug)]
 pub struct glob_t {
@@ -52,6 +53,7 @@ pub struct glob_t {
     __opaque: *mut c_void, // Vec<*mut c_char>
 }
 
+#[linkage = "weak"] // GNU prefers its own glob e.g. in Make
 #[no_mangle]
 pub unsafe extern "C" fn glob(
     pattern: *const c_char,
@@ -145,6 +147,7 @@ pub unsafe extern "C" fn glob(
     0
 }
 
+#[linkage = "weak"] // GNU prefers its own glob e.g. in Make
 #[no_mangle]
 pub unsafe extern "C" fn globfree(pglob: *mut glob_t) {
     // Retake ownership