asio: unbreak musl

Do not change the code path for glibc by using a macro
MUSL_LIBC which is defined only if target is *-musl.

srcpkgs/asio/patches/musl_strerror_r.patch

@@ -0,0 +1,11 @@
+--- include/asio/impl/error_code.ipp	2015-03-23 21:28:30.000000000 +0100
++++ include/asio/impl/error_code.ipp	2015-07-12 14:49:24.720507062 +0200
+@@ -100,7 +100,7 @@
+ #elif defined(__MACH__) && defined(__APPLE__) \
+   || defined(__NetBSD__) || defined(__FreeBSD__) || defined(__OpenBSD__) \
+   || defined(_AIX) || defined(__hpux) || defined(__osf__) \
+-  || defined(__ANDROID__)
++  || defined(__ANDROID__) || defined(MUSL_LIBC)
+     char buf[256] = "";
+     using namespace std;
+     strerror_r(value, buf, sizeof(buf));

srcpkgs/asio/template

@@ -1,7 +1,7 @@
 # Template file for 'asio'
 pkgname=asio
 version=1.10.6
-revision=1
+revision=2
 build_style=gnu-configure
 makedepends="boost-devel"
 depends="boost-devel"
@@ -11,3 +11,11 @@ license="Boost"
 homepage="http://asio.sourceforge.net"
 distfiles="${SOURCEFORGE_SITE}/asio/asio-${version}.tar.bz2"
 checksum=e0d71c40a7b1f6c1334008fb279e7361b32a063e020efd21e40d9d8ff037195e
+
+pre_configure() {
+	case "$XBPS_TARGET_MACHINE" in
+		*-musl) # Enable strerror_r(3) version for musl libc
+			sed -e "/#define ASIO_IMPL_ERROR_CODE_IPP/a #define MUSL_LIBC" \
+				-i ${wrksrc}/include/asio/impl/error_code.ipp
+	esac
+}