Add linux-loongarch64 support.

This is only supported for cross-compilation for now; toolset packages won't be
available until Zig 0.15.0 at the earliest.

Part of #182.

Author: alexrp

Diff for: src/sdk/build/Vezel.Zig.Sdk.Cross.Host.targets

@@ -13,6 +13,7 @@
     <PropertyGroup>
         <HostArchitecture Condition="$(HostRuntimeIdentifier.EndsWith('-arm64'))">aarch64</HostArchitecture>
         <HostArchitecture Condition="$(HostRuntimeIdentifier.EndsWith('-arm'))">arm</HostArchitecture>
+        <HostArchitecture Condition="$(HostRuntimeIdentifier.EndsWith('-loongarch64'))">loongarch64</HostArchitecture>
         <HostArchitecture Condition="$(HostRuntimeIdentifier.EndsWith('-ppc64le'))">powerpc64le</HostArchitecture>
         <HostArchitecture Condition="$(HostRuntimeIdentifier.EndsWith('-riscv64'))">riscv64</HostArchitecture>
         <HostArchitecture Condition="$(HostRuntimeIdentifier.EndsWith('-s390x'))">s390x</HostArchitecture>

Diff for: src/sdk/build/Vezel.Zig.Sdk.Cross.Target.targets

@@ -13,6 +13,7 @@
     <PropertyGroup>
         <TargetArchitecture Condition="$(TargetRuntimeIdentifier.EndsWith('-arm64'))">aarch64</TargetArchitecture>
         <TargetArchitecture Condition="$(TargetRuntimeIdentifier.EndsWith('-arm'))">arm</TargetArchitecture>
+        <TargetArchitecture Condition="$(TargetRuntimeIdentifier.EndsWith('-loongarch64'))">loongarch64</TargetArchitecture>
         <TargetArchitecture Condition="$(TargetRuntimeIdentifier.EndsWith('-ppc64le'))">powerpc64le</TargetArchitecture>
         <TargetArchitecture Condition="$(TargetRuntimeIdentifier.EndsWith('-riscv64'))">riscv64</TargetArchitecture>
         <TargetArchitecture Condition="$(TargetRuntimeIdentifier.EndsWith('-s390x'))">s390x</TargetArchitecture>
@@ -29,6 +30,7 @@
     <PropertyGroup Condition="$(TargetRuntimeIdentifier.StartsWith('linux-'))">
         <TargetSystem>linux</TargetSystem>
         <TargetSystemVersion>3.10</TargetSystemVersion>
+        <TargetSystemVersion Condition="'$(TargetArchitecture)' == 'loongarch64'">5.19</TargetSystemVersion>
         <TargetSystemVersion Condition="'$(TargetArchitecture)' == 'powerpc64le'">3.14</TargetSystemVersion>
         <TargetSystemVersion Condition="'$(TargetArchitecture)' == 'riscv64'">4.15</TargetSystemVersion>
     </PropertyGroup>
@@ -69,6 +71,7 @@
 
     <PropertyGroup Condition="'$(TargetLibrary)' == 'glibc'">
         <TargetLibraryVersion>2.17</TargetLibraryVersion>
+        <TargetLibraryVersion Condition="'$(TargetArchitecture)' == 'loongarch64'">2.36</TargetLibraryVersion>
         <TargetLibraryVersion Condition="'$(TargetArchitecture)' == 'powerpc64le'">2.19</TargetLibraryVersion>
         <TargetLibraryVersion Condition="'$(TargetArchitecture)' == 'riscv64'">2.27</TargetLibraryVersion>
     </PropertyGroup>

Diff for: src/sdk/build/Vezel.Zig.Sdk.Defaults.targets

@@ -70,12 +70,14 @@
         <RuntimeIdentifiers Condition="'$(RuntimeIdentifiers)' == ''">
             linux-arm;
             linux-arm64;
+            linux-loongarch64;
             linux-ppc64le;
             linux-riscv64;
             linux-s390x;
             linux-x64;
             linux-musl-arm;
             linux-musl-arm64;
+            linux-musl-loongarch64;
             linux-musl-ppc64le;
             linux-musl-riscv64;
             linux-musl-s390x;