Move cosmo-clang to libexec

The cosmo-clang command shouldn't be in the bin/ folder of cosmocc. It's
intended as an implementation detail of `cosmocc -mclang`.

Fixes #1317

Author: jart

tool/cosmocc/bin/cosmocc

@@ -89,10 +89,10 @@ use_gcc() {
 
 use_clang() {
   CLANG=1
-  CC_X86_64="$BIN/cosmo-clang"
-  CC_AARCH64="$BIN/cosmo-clang"
-  CXX_X86_64="$BIN/cosmo-clang"
-  CXX_AARCH64="$BIN/cosmo-clang"
+  CC_X86_64="$BIN/../libexec/clang"
+  CC_AARCH64="$BIN/../libexec/clang"
+  CXX_X86_64="$BIN/../libexec/clang"
+  CXX_AARCH64="$BIN/../libexec/clang"
   TARGET_X86_64="--target=x86_64"
   TARGET_AARCH64="--target=aarch64"
   FPORTCOSMO=

tool/cosmocc/package.sh

@@ -185,7 +185,7 @@ if [ ! -x bin/x86_64-linux-cosmo-gcc ]; then
   rm -f aarch64-gcc.zip
   rm -f x86_64-gcc.zip
   rm -f llvm.zip
-  mv bin/clang-19 bin/cosmo-clang
+  mv bin/clang-19 libexec/clang  # use `cosmocc -mclang` instead
 fi
 rm -f bin/*-cpp
 rm -f bin/*-gcc-*