llvm: Avoid looking at /proc/self/exe

LLVM looks at /proc/self/exe to determine which binary has been called.
This does not work with the proposed changes for termux-exec:
termux/termux-exec#24

Luckily the fallback to look at argv0 works instead.

packages/libllvm/build.sh

@@ -5,7 +5,7 @@ TERMUX_PKG_LICENSE_FILE="llvm/LICENSE.TXT"
 TERMUX_PKG_MAINTAINER="@finagolfin"
 LLVM_MAJOR_VERSION=16
 TERMUX_PKG_VERSION=${LLVM_MAJOR_VERSION}.0.6
-TERMUX_PKG_REVISION=2
+TERMUX_PKG_REVISION=3
 TERMUX_PKG_SHA256=ce5e71081d17ce9e86d7cbcfa28c4b04b9300f8fb7e78422b1feb6bc52c3028e
 TERMUX_PKG_SRCURL=https://github.com/llvm/llvm-project/releases/download/llvmorg-$TERMUX_PKG_VERSION/llvm-project-$TERMUX_PKG_VERSION.src.tar.xz
 TERMUX_PKG_HOSTBUILD=true

packages/libllvm/llvm-lib-Support-Unix-Path.inc.patch

@@ -0,0 +1,19 @@
+diff -u -r ../orig-src/llvm/lib/Support/Unix/Path.inc ./llvm/lib/Support/Unix/Path.inc
+--- ../orig-src/llvm/lib/Support/Unix/Path.inc	2023-09-29 21:36:47.056335287 +0000
++++ ./llvm/lib/Support/Unix/Path.inc	2023-09-29 21:40:31.091417185 +0000
+@@ -252,6 +252,7 @@
+     return exe_path;
+ #elif defined(__linux__) || defined(__CYGWIN__) || defined(__gnu_hurd__)
+   char exe_path[PATH_MAX];
++#ifndef __ANDROID__ /* Avoid looking at /proc/self/exe, as it does not work with termux-exec linker wrapping */
+   const char *aPath = "/proc/self/exe";
+   if (sys::fs::exists(aPath)) {
+     // /proc is not always mounted under Linux (chroot for example).
+@@ -280,6 +281,7 @@
+       return std::string(real_path);
+ #endif
+   }
++#endif
+   // Fall back to the classical detection.
+   if (getprogpath(exe_path, argv0))
+     return exe_path;