install.texi: gcn - suggest to use Newlib with simd math fix [PR119325]

install.texi: gcn - suggest to use Newlib with simd math fix [PR119325]

Suggest a Newlib with a fix for the SIMD math issue.  Newlib commit:
https://sourceware.org/git/?p=newlib-cygwin.git;a=commitdiff;h=2ef1a37e7

Additionally, for generic support in ROCm, it is expected that 6.4 will
added the support; the current version is 6.3.3 and it does not support it;
bump >6.3.2 to >6.3.3 in install.texi to avoid doubts.

gcc/ChangeLog:

	PR middle-end/119325

	* doc/install.texi (gcn): Change ROCm > 6.3.2 to >6.3.3 for generic
	support; mention Newlib commit that fixes a SIMD math issue.