sys-apps/isapnptools: fix compile on musl

Copied this patch from ::musl overlay (whose origin is unknown
since it appeared as part of initial commit in that repo).

The change itself consists of 2 fixes:

1. Adding "#include <stdlib.h>" which is safe
2. converting conditional include into consistent "#include <sys/io.h>"
   which should work on all libc we care about in Gentoo.

I don't see a reason to cause rebuild with this patch, since where it
managed to build work as needed, so no need for revbump.

Closes: https://bugs.gentoo.org/712764
Closes: https://bugs.gentoo.org/889557
Signed-off-by: Arthur Zamarin <arthurzam@gentoo.org>

sys-apps/isapnptools/files/isapnptools-1.27-musl.patch

@@ -0,0 +1,30 @@
+--- a/include/isapnp/iopl.h
++++ b/include/isapnp/iopl.h
+@@ -52,15 +52,7 @@ extern "C" {
+ #include <dos.h>
+ #else
+ #ifndef _OS2_
+-#  if defined __GLIBC__ && __GLIBC__ >= 2
+-#    include <sys/io.h>
+-#  else
+-#    ifdef _AXP_
+-#       include <sys/io.h>
+-#    else
+-#       include <asm/io.h>
+-#    endif
+-#  endif	      	   /* __GLIBC__ */
++#include <sys/io.h>
+ #else
+ #include <sys/hw.h>
+ #endif /* _OS2_ */
+--- a/src/pnp-select.c
++++ b/src/pnp-select.c
+@@ -6,6 +6,8 @@
+    Foundation.
+ */
+ 
++#include <stdlib.h>
++
+ #ifdef HAVE_CONFIG_H
+ #include <config.h>
+ #endif

sys-apps/isapnptools/isapnptools-1.27-r1.ebuild

@@ -17,6 +17,7 @@ PATCHES=(
 	"${FILESDIR}"/${P}-include.patch
 	"${FILESDIR}"/${P}-fno-common.patch
 	"${FILESDIR}"/${P}-incompatible-pointer-types.patch
+	"${FILESDIR}"/${P}-musl.patch
 )
 
 src_configure() {