ndk-patches: Don't declare sem_{open,close,unlink}

but instead declare `libandroid_sem_{open,close,unlink}` defined in
`libandroid-posix-semaphore`.

ndk-patches/semaphore.h.patch

@@ -0,0 +1,18 @@
+--- ./usr/include/semaphore.h.orig
++++ ./usr/include/semaphore.h
+@@ -71,9 +71,14 @@
+ int sem_trywait(sem_t* __sem);
+ int sem_wait(sem_t* __sem);
+ 
+-/* These aren't actually implemented. */
++#undef sem_open
++#define sem_open libandroid_sem_open
+ sem_t* sem_open(const char* __name, int _flags, ...);
++#undef sem_close
++#define sem_close libandroid_sem_close
+ int sem_close(sem_t* __sem);
++#undef sem_unlink
++#define sem_unlink libandroid_sem_unlink
+ int sem_unlink(const char* __name);
+ 
+ __END_DECLS

scripts/build/termux_step_start_build.sh

@@ -2,7 +2,7 @@ termux_step_start_build() {
 	TERMUX_STANDALONE_TOOLCHAIN="$TERMUX_COMMON_CACHEDIR/android-r${TERMUX_NDK_VERSION}-api-${TERMUX_PKG_API_LEVEL}"
 	# Bump the below version if a change is made in toolchain setup to ensure
 	# that everyone gets an updated toolchain:
-	TERMUX_STANDALONE_TOOLCHAIN+="-v8"
+	TERMUX_STANDALONE_TOOLCHAIN+="-v9"
 
 	# shellcheck source=/dev/null
 	source "$TERMUX_PKG_BUILDER_SCRIPT"