small fix for llvm build

I'm getting build failures when building with meson and llvm enabled, 
like this:

[1/112] Generating src/backend/jit/llvm/llvmjit_types.bc with a custom 
command
FAILED: src/backend/jit/llvm/llvmjit_types.bc
/usr/local/bin/ccache /usr/local/Cellar/llvm/18.1.6/bin/clang -c -o 
src/backend/jit/llvm/llvmjit_types.bc 
../src/backend/jit/llvm/llvmjit_types.c -flto=thin -emit-llvm -MD -MQ 
src/backend/jit/llvm/llvmjit_types.bc -MF 
src/backend/jit/llvm/llvmjit_types.c.bc.d -O2 -Wno-ignored-attributes 
-Wno-empty-body -fno-strict-aliasing -fwrapv -I./src/include 
-I./src/backend/utils/misc -I../src/include
In file included from ../src/backend/jit/llvm/llvmjit_types.c:27:
In file included from ../src/include/postgres.h:45:
../src/include/c.h:75:10: fatal error: 'libintl.h' file not found
    75 | #include <libintl.h>
       |          ^~~~~~~~~~~
1 error generated.


The reason is that libintl.h is at /usr/local/include/libintl.h, but 
that is not in the include path for this command.  I have 
-I/usr/local/include in CPPFLAGS in the environment, which is why the 
normal compilation commands pick it up, but this is not used by this 
custom command.

Wit this small patch I can make it work:

diff --git a/src/backend/jit/llvm/meson.build 
b/src/backend/jit/llvm/meson.build
index 41c759f73c5..4a4232661ba 100644
--- a/src/backend/jit/llvm/meson.build
+++ b/src/backend/jit/llvm/meson.build
@@ -63,6 +63,7 @@ bitcode_cflags = ['-fno-strict-aliasing', '-fwrapv']
  if llvm.version().version_compare('=15.0')
    bitcode_cflags += ['-Xclang', '-no-opaque-pointers']
  endif
+bitcode_cflags += get_option('c_args')
  bitcode_cflags += cppflags

  # XXX: Worth improving on the logic to find directories here


Is that correct?