platform-support.md: remove references to not-yet upstreamed targets.

Author: he32

src/doc/rustc/src/platform-support.md

@@ -259,7 +259,6 @@ target | std | host | notes
 `hexagon-unknown-linux-musl` | ? |  |
 `i386-apple-ios` | ✓ |  | 32-bit x86 iOS
 [`i586-pc-nto-qnx700`](platform-support/nto-qnx.md) | * |  | 32-bit x86 QNX Neutrino 7.0 RTOS |
-[`i586-unknown-netbsd`](platform-support/netbsd.md) | ✓ | ✓ | NetBSD/i386 restricted to Pentium insns
 `i686-apple-darwin` | ✓ | ✓ | 32-bit macOS (10.7+, Lion+)
 `i686-pc-windows-msvc` | * |  | 32-bit Windows XP support
 `i686-unknown-haiku` | ✓ | ✓ | 32-bit Haiku
@@ -275,7 +274,6 @@ target | std | host | notes
 `mipsel-sony-psp` | * |  | MIPS (LE) Sony PlayStation Portable (PSP)
 [`mipsel-sony-psx`](platform-support/mipsel-sony-psx.md) | * |  | MIPS (LE) Sony PlayStation 1 (PSX)
 `mipsel-unknown-linux-uclibc` | ✓ |  | MIPS (LE) Linux with uClibc
-[`mipsel-unknown-netbsd`](platform-support/netbsd.md) | ✓ | ✓ | MIPS (LE) on NetBSD, requires mips32 CPU
 `mipsel-unknown-none` | * |  | Bare MIPS (LE) softfloat
 `mipsisa32r6-unknown-linux-gnu` | ? |  |
 `mipsisa32r6el-unknown-linux-gnu` | ? |  |