Configure QDLDL include files to build directory

[imciner2]

Configuring into the source tree means the configured headers will clash if you try to build multiple configurations at once, so instead configure them into the build directory and then use those and install those to ensure each configuration has the correct header.

[coveralls]

Pull Request Test Coverage Report for Build 8940072029

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

---

Totals
Change from base Build 8940061973:	0.0%
Covered Lines:	87
Relevant Lines:	87

---

💛 - Coveralls