Fix arg callout in substring expansion (bash)

[tomkaragounis]

Noticed that custom build flags were not being correctly assigned to the CUSTOM_CMAKE_CXX_FLAG variable in the build.sh script. Not sure how this got modified as I would still expect $1 to contain the full arg. Works with below fix.

Error examples:
./build.sh CUSTOM_BUILD_FLAGS="-DHAVE_MAT_EVT_TRACEID=1" debug
Current directory: /home/tomkar
BUILD_TYPE = Debug
Using current machine MAC_ARCH = x86_64
custom build flags = ""

./build.sh CUSTOM_BUILD_FLAGS -DHAVE_MAT_EVT_TRACEID=1 debug
Current directory: /home/tomkar
BUILD_TYPE = Debug
Using current machine MAC_ARCH = x86_64
custom build flags = "EID=1"

"EID=1" is 19 chars into -DHAVE_MAT_EVT_TRACEID=1, so offset is activated here, just for the next argument instead of the CUSTOM_BUILD_FLAGS

[ThomsonTan]

As we expect ${1} should match $PARAM1, could we try to understand why and how it is modified?

[tomkaragounis]

As we expect ${1} should match $PARAM1, could we try to understand why and how it is modified?

I am actually not very well versed in bash, so I do not understand why the behavior is not working correctly. I have been testing it out locally and realized the problem when I try adding my own custom args