man5/elf.5: srcfix: Correct the misuse of two-fonts macros

Changes are based on the latest (23th Februar 2020) revision of my
local git repository.

Correct the misuse of a two-font macro, which function is to

1) use the first font for each odd numbered argument and the second font for all others.

2) join the arguments without an intervening space.

There is no change in the output.

---
 man5/elf.5 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index f32df19e8..ffaca8549 100644
@@ -2145,7 +2145,7 @@ The extensions for
 .IR e_phnum ,
 .I e_shnum
 and
-.IR e_shstrndx
+.I e_shstrndx
 respectively are
 Linux extensions.
 Sun, BSD and AMD64 also support them; for further information,

2.25.0