[lldb] Fix command-expr-diagnostics.test for Windows (#112109)

This adds a minor change to command-expr-diagnostics.test to make
it pass on windows. Clang produces PDB on windows by default which
was ignoring main symbol due to optimization. The problem is fixed
by adding -gdwarf to commandline, making sure dwarf debug info gets
generated on both Windows and Linux.

Author: omjavaid

lldb/test/Shell/Commands/command-expr-diagnostics.test

@@ -17,7 +17,7 @@
 # CHECK3: {{^                         error: use of undeclared identifier 'a'}}
 
 # RUN: echo "int main(){return 0;}">%t.c
-# RUN: %clang_host %t.c -o %t.exe
+# RUN: %clang_host %t.c -gdwarf -o %t.exe
 # RUN: echo quit | %lldb %t.exe -o "b main" -o r -o \
 # RUN: "expr --top-level -- template<typename T> T FOO(T x) { return x/2;}" -o \
 # RUN: "expression -- FOO(\"\")" 2>&1 | FileCheck %s --check-prefix=CHECK4