makepkg.conf: drop -fvar-tracking-assignments flag

According to gcc(1), this flag (like -fvar-tracking) is enabled by
default when compiling with optimization and debugging information.

As an additional benefit, packages building with the clang compiler
will work with the default flags without having to remove this flag
due to not being recognized by clang.

makepkg-x86_64.conf

@@ -49,8 +49,8 @@ LDFLAGS="-Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now"
 #-- Make Flags: change this for DistCC/SMP systems
 #MAKEFLAGS="-j2"
 #-- Debugging flags
-DEBUG_CFLAGS="-g -fvar-tracking-assignments"
-DEBUG_CXXFLAGS="-g -fvar-tracking-assignments"
+DEBUG_CFLAGS="-g"
+DEBUG_CXXFLAGS="$DEBUG_CFLAGS"
 #DEBUG_RUSTFLAGS="-C debuginfo=2"
 
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