[scudo] Add 'inline' to static secondary.h function

This patches an error flaged by Fuchsia builds e.g.
https://ci.chromium.org/ui/p/turquoise/builders/global.try/core.x64-asan/b8779376650819379137/overview)

```
build failed:

[87176/332302](525) CXX user.libc_x64-asan-ubsan/obj/zircon/system/ulib/c/scudo/gwp-asan-info.gwp_asan_info.cc.o
FAILED: user.libc_x64-asan-ubsan/obj/zircon/system/ulib/c/scudo/gwp-asan-info.gwp_asan_info.cc.o
../../prebuilt/third_party/python3/linux-x64/bin/python3.8 -S ../../build/rbe/cxx_remote_wrapper.py --exec_strategy=remote_local_fallback --  ../../prebuilt/third_party/clang/linux-x64/bin/clang++ -MD -MF user.libc_x64-asan-ubsan/obj/zircon/system/ulib/c/scudo/gwp-asan-info.gwp_asan_info.cc.o.d -o user.libc_x64-asan-ubsan/obj/zircon/system/ulib/c/scudo/gwp-asan-info.gwp_asan_info.cc.o -D_LIBCPP...
In file included from ../../zircon/system/ulib/c/scudo/gwp_asan_info.cc:7:
In file included from ../../third_party/scudo/src/allocator_config.h:12:
In file included from ../../third_party/scudo/src/combined.h:22:
../../third_party/scudo/src/secondary.h:67:13: error: 'static' function 'unmap' declared in header file should be declared 'static inline' [-Werror,-Wunneeded-internal-declaration]
static void unmap(LargeBlock::Header *H) {
            ^
1 error generated.
```

Differential Revision: https://reviews.llvm.org/D152038

Author: Caslyn

compiler-rt/lib/scudo/standalone/secondary.h

@@ -64,7 +64,7 @@ template <typename Config> static Header *getHeader(const void *Ptr) {
 
 } // namespace LargeBlock
 
-static void unmap(LargeBlock::Header *H) {
+static inline void unmap(LargeBlock::Header *H) {
   // Note that the `H->MapMap` is stored on the pages managed by itself. Take
   // over the ownership before unmap() so that any operation along with unmap()
   // won't touch inaccessible pages.